pdf: enable eslint checks for no-var and prefer-const

Most of this change was automated by running `eslint --fix` but a
few cases were resolved manually (in particular global definitions
and typedefs).

Bug: 792774
Change-Id: Iea4e373a088d7d276975bf946a738bc9d81772c3
Reviewed-on: https://chromium-review.googlesource.com/c/1355302
Commit-Queue: dstockwell <dstockwell@chromium.org>
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#612985}

chrome/browser/resources/pdf/.eslintrc.js

+// Copyright 2018 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+module.exports = {
+  env: {
+    'browser': true,
+    'es6': true,
+  },
+  rules: {
+    'no-var': 'error',
+    'prefer-const': 'error',
+  },
+};

chrome/browser/resources/pdf/browser_api.js

@@ -142,7 +142,7 @@ class BrowserApi {
       return;
 
     chrome.tabs.onZoomChange.addListener(info => {
-      var zoomChangeInfo =
+      const zoomChangeInfo =
           /** @type {{tabId: number, newZoomFactor: number}} */ (info);
       if (zoomChangeInfo.tabId != this.streamInfo_.tabId)
         return;
@@ -172,7 +172,7 @@ function createBrowserApiForMimeHandlerView() {
            chrome.mimeHandlerPrivate.getStreamInfo(resolve);
          })
       .then(function(streamInfo) {
-        let promises = [];
+        const promises = [];
         let zoomBehavior = BrowserApi.ZoomBehavior.NONE;
         if (streamInfo.tabId != -1) {
           zoomBehavior = streamInfo.embedded ?
@@ -204,8 +204,8 @@ function createBrowserApiForMimeHandlerView() {
  *     from the URL.
  */
 function createBrowserApiForPrintPreview() {
-  let url = window.location.search.substring(1);
-  let streamInfo = {
+  const url = window.location.search.substring(1);
+  const streamInfo = {
     streamUrl: url,
     originalUrl: url,
     responseHeaders: {},

chrome/browser/resources/pdf/elements/viewer-bookmark/viewer-bookmark.js

@@ -21,11 +21,11 @@
  *   children: !Array<!Bookmark>
  * }}
  */
-var Bookmark;
+let Bookmark;
 
 (function() {
 /** Amount that each level of bookmarks is indented by (px). */
-var BOOKMARK_INDENT = 20;
+const BOOKMARK_INDENT = 20;
 
 Polymer({
   is: 'viewer-bookmark',

chrome/browser/resources/pdf/elements/viewer-page-indicator/viewer-page-indicator.js

@@ -18,7 +18,7 @@ Polymer({
 
   /** @override */
   ready: function() {
-    var callback = this.fadeIn.bind(this, 2000);
+    const callback = this.fadeIn.bind(this, 2000);
     window.addEventListener('scroll', function() {
       requestAnimationFrame(callback);
     });
@@ -30,7 +30,7 @@ Polymer({
 
   /** @param {number} displayTime */
   fadeIn: function(displayTime) {
-    var percent = window.scrollY /
+    const percent = window.scrollY /
         (document.scrollingElement.scrollHeight -
          document.documentElement.clientHeight);
     this.style.top =

chrome/browser/resources/pdf/elements/viewer-page-selector/viewer-page-selector.js

@@ -30,7 +30,7 @@ Polymer({
   },
 
   pageNoCommitted: function() {
-    var page = parseInt(this.pageSelector.value, 10);
+    const page = parseInt(this.pageSelector.value, 10);
 
     if (!isNaN(page) && page <= this.docLength && page > 0)
       this.fire('change-page', {page: page - 1, origin: 'pageselector'});
@@ -41,7 +41,7 @@ Polymer({
 
   /** @private */
   docLengthChanged_: function() {
-    var numDigits = this.docLength.toString().length;
+    const numDigits = this.docLength.toString().length;
     this.pageSelector.style.width = numDigits + 'ch';
     // Set both sides of the slash to the same width, so that the layout is
     // exactly centered.

chrome/browser/resources/pdf/elements/viewer-password-screen/viewer-password-screen.js

@@ -25,7 +25,7 @@ Polymer({
   },
 
   deny: function() {
-    var password = /** @type {!CrInputElement} */ (this.$.password);
+    const password = /** @type {!CrInputElement} */ (this.$.password);
     password.disabled = false;
     this.$.submit.disabled = false;
     this.invalid = true;
@@ -33,7 +33,7 @@ Polymer({
   },
 
   submit: function() {
-    var password = /** @type {!CrInputElement} */ (this.$.password);
+    const password = /** @type {!CrInputElement} */ (this.$.password);
     if (password.value.length == 0)
       return;
     password.disabled = true;

chrome/browser/resources/pdf/elements/viewer-toolbar-dropdown/viewer-toolbar-dropdown.js

@@ -6,13 +6,13 @@
 /**
  * Size of additional padding in the inner scrollable section of the dropdown.
  */
-var DROPDOWN_INNER_PADDING = 12;
+const DROPDOWN_INNER_PADDING = 12;
 
 /** Size of vertical padding on the outer #dropdown element. */
-var DROPDOWN_OUTER_PADDING = 2;
+const DROPDOWN_OUTER_PADDING = 2;
 
 /** Minimum height of toolbar dropdowns (px). */
-var MIN_DROPDOWN_HEIGHT = 200;
+const MIN_DROPDOWN_HEIGHT = 200;
 
 Polymer({
   is: 'viewer-toolbar-dropdown',
@@ -76,8 +76,8 @@ Polymer({
   },
 
   updateMaxHeight: function() {
-    var scrollContainer = this.$['scroll-container'];
-    var height = this.lowerBound - scrollContainer.getBoundingClientRect().top -
+    const scrollContainer = this.$['scroll-container'];
+    let height = this.lowerBound - scrollContainer.getBoundingClientRect().top -
         DROPDOWN_INNER_PADDING;
     height = Math.max(height, MIN_DROPDOWN_HEIGHT);
     scrollContainer.style.maxHeight = height + 'px';
@@ -100,7 +100,7 @@ Polymer({
   },
 
   animateEntry_: function() {
-    var maxHeight =
+    let maxHeight =
         this.$.dropdown.getBoundingClientRect().height - DROPDOWN_OUTER_PADDING;
 
     if (maxHeight < 0)

chrome/browser/resources/pdf/elements/viewer-zoom-toolbar/viewer-zoom-toolbar.js

@@ -4,8 +4,8 @@
 
 (function() {
 
-var FIT_TO_PAGE_BUTTON_STATE = 0;
-var FIT_TO_WIDTH_BUTTON_STATE = 1;
+const FIT_TO_PAGE_BUTTON_STATE = 0;
+const FIT_TO_WIDTH_BUTTON_STATE = 1;
 
 Polymer({
   is: 'viewer-zoom-toolbar',
@@ -49,7 +49,7 @@ Polymer({
     this.fitToggle();
 
     // Toggle the button state since there was no mouse click.
-    var button = this.$['fit-button'];
+    const button = this.$['fit-button'];
     button.activeIndex =
         (button.activeIndex == FIT_TO_WIDTH_BUTTON_STATE ?
              FIT_TO_PAGE_BUTTON_STATE :
@@ -64,7 +64,7 @@ Polymer({
     this.fireFitToChangedEvent_(fittingType, false);
 
     // Set the button state since there was no mouse click.
-    var nextButtonState =
+    const nextButtonState =
         (fittingType == FittingType.FIT_TO_WIDTH ? FIT_TO_PAGE_BUTTON_STATE :
                                                    FIT_TO_WIDTH_BUTTON_STATE);
     this.$['fit-button'].activeIndex = nextButtonState;
@@ -115,5 +115,4 @@ Polymer({
     }
   },
 });
-
 })();

chrome/browser/resources/pdf/gesture_detector.js

@@ -21,7 +21,7 @@ class GestureDetector {
         /** @type {function(!Event)} */ (this.onTouchStart_.bind(this)),
         {passive: true});
 
-    let boundOnTouch =
+    const boundOnTouch =
         /** @type {function(!Event)} */ (this.onTouch_.bind(this));
     this.element_.addEventListener('touchmove', boundOnTouch, {passive: true});
     this.element_.addEventListener('touchend', boundOnTouch, {passive: true});
@@ -85,9 +85,9 @@ class GestureDetector {
    * @private
    */
   notify_(pinchEvent) {
-    let listeners = this.listeners_.get(pinchEvent.type);
+    const listeners = this.listeners_.get(pinchEvent.type);
 
-    for (let l of listeners)
+    for (const l of listeners)
       l(pinchEvent);
   }
 
@@ -117,15 +117,15 @@ class GestureDetector {
     if (!this.pinchStartEvent_)
       return;
 
-    let lastEvent = /** @type {!TouchEvent} */ (this.lastEvent_);
+    const lastEvent = /** @type {!TouchEvent} */ (this.lastEvent_);
 
     // Check if the pinch ends with the current event.
     if (event.touches.length < 2 ||
         lastEvent.touches.length !== event.touches.length) {
-      let startScaleRatio =
+      const startScaleRatio =
           GestureDetector.pinchScaleRatio_(lastEvent, this.pinchStartEvent_);
-      let center = GestureDetector.center_(lastEvent);
-      let endEvent = {
+      const center = GestureDetector.center_(lastEvent);
+      const endEvent = {
         type: 'pinchend',
         startScaleRatio: startScaleRatio,
         center: center
@@ -136,10 +136,10 @@ class GestureDetector {
       return;
     }
 
-    let scaleRatio = GestureDetector.pinchScaleRatio_(event, lastEvent);
-    let startScaleRatio =
+    const scaleRatio = GestureDetector.pinchScaleRatio_(event, lastEvent);
+    const startScaleRatio =
         GestureDetector.pinchScaleRatio_(event, this.pinchStartEvent_);
-    let center = GestureDetector.center_(event);
+    const center = GestureDetector.center_(event);
     this.notify_({
       type: 'pinchupdate',
       scaleRatio: scaleRatio,
@@ -169,11 +169,11 @@ class GestureDetector {
 
     event.preventDefault();
 
-    let wheelScale = Math.exp(-event.deltaY / 100);
+    const wheelScale = Math.exp(-event.deltaY / 100);
     // Clamp scale changes from the wheel event as they can be
     // quite dramatic for non-synthetic ctrl-wheels.
-    let scale = Math.min(1.25, Math.max(0.75, wheelScale));
-    let position = {x: event.clientX, y: event.clientY};
+    const scale = Math.min(1.25, Math.max(0.75, wheelScale));
+    const position = {x: event.clientX, y: event.clientY};
 
     if (this.accumulatedWheelScale_ == null) {
       this.accumulatedWheelScale_ = 1.0;
@@ -196,8 +196,8 @@ class GestureDetector {
       window.clearTimeout(this.wheelEndTimeout_);
       this.wheelEndTimeout_ = null;
     }
-    let gestureEndDelayMs = 100;
-    let endEvent = {
+    const gestureEndDelayMs = 100;
+    const endEvent = {
       type: 'pinchend',
       startScaleRatio: this.accumulatedWheelScale_,
       center: position
@@ -220,8 +220,8 @@ class GestureDetector {
    * @private
    */
   static pinchScaleRatio_(event, prevEvent) {
-    let distance1 = GestureDetector.distance_(prevEvent);
-    let distance2 = GestureDetector.distance_(event);
+    const distance1 = GestureDetector.distance_(prevEvent);
+    const distance2 = GestureDetector.distance_(event);
     return distance1 === 0 ? null : distance2 / distance1;
   }
 
@@ -233,10 +233,10 @@ class GestureDetector {
    * @private
    */
   static distance_(event) {
-    let touch1 = event.touches[0];
-    let touch2 = event.touches[1];
-    let dx = touch1.clientX - touch2.clientX;
-    let dy = touch1.clientY - touch2.clientY;
+    const touch1 = event.touches[0];
+    const touch2 = event.touches[1];
+    const dx = touch1.clientX - touch2.clientX;
+    const dy = touch1.clientY - touch2.clientY;
     return Math.sqrt(dx * dx + dy * dy);
   }
 
@@ -248,8 +248,8 @@ class GestureDetector {
    * @private
    */
   static center_(event) {
-    let touch1 = event.touches[0];
-    let touch2 = event.touches[1];
+    const touch1 = event.touches[0];
+    const touch2 = event.touches[1];
     return {
       x: (touch1.clientX + touch2.clientX) / 2,
       y: (touch1.clientY + touch2.clientY) / 2

chrome/browser/resources/pdf/main.js

@@ -9,7 +9,7 @@
  *
  * @type Object
  */
-var viewer;
+window.viewer = null;
 
 
 (function() {
@@ -19,7 +19,7 @@ var viewer;
  *
  * @type Array
  */
-var pendingMessages = [];
+const pendingMessages = [];
 
 /**
  * Handles events that are received prior to the PDFViewer being created.
@@ -72,7 +72,7 @@ function main() {
   // Set up an event listener to catch scripting messages which are sent prior
   // to the PDFViewer being created.
   window.addEventListener('message', handleScriptingMessage, false);
-  var chain = createBrowserApi();
+  let chain = createBrowserApi();
 
   // Content settings may not be present in test environments.
   if (chrome.contentSettings)

chrome/browser/resources/pdf/navigator.js

@@ -111,7 +111,7 @@ Navigator.prototype = {
     if (url.charAt(0) == '#') {
       // if '#' is already present in |originalUrl| then remove old fragment
       // and add new url fragment.
-      var hashIndex = this.originalUrl_.search('#');
+      const hashIndex = this.originalUrl_.search('#');
       if (hashIndex != -1)
         url = this.originalUrl_.substring(0, hashIndex) + url;
       else
@@ -158,17 +158,17 @@ Navigator.prototype = {
    * @private
    */
   onViewportReceived_: function(viewportPosition) {
-    var originalUrl = this.originalUrl_;
-    var hashIndex = originalUrl.search('#');
+    let originalUrl = this.originalUrl_;
+    let hashIndex = originalUrl.search('#');
     if (hashIndex != -1)
       originalUrl = originalUrl.substring(0, hashIndex);
 
-    var newUrl = viewportPosition.url;
+    let newUrl = viewportPosition.url;
     hashIndex = newUrl.search('#');
     if (hashIndex != -1)
       newUrl = newUrl.substring(0, hashIndex);
 
-    var pageNumber = viewportPosition.page;
+    const pageNumber = viewportPosition.page;
     if (pageNumber != undefined && originalUrl == newUrl)
       this.viewport_.goToPage(pageNumber);
     else
@@ -224,16 +224,17 @@ Navigator.prototype = {
 
     // Check for absolute paths.
     if (url.startsWith('/')) {
-      var schemeEndIndex = this.originalUrl_.indexOf('://');
-      var firstSlash = this.originalUrl_.indexOf('/', schemeEndIndex + 3);
+      const schemeEndIndex = this.originalUrl_.indexOf('://');
+      const firstSlash = this.originalUrl_.indexOf('/', schemeEndIndex + 3);
       // e.g. http://www.foo.com/bar -> http://www.foo.com
-      var domain = firstSlash != -1 ? this.originalUrl_.substr(0, firstSlash) :
-                                      this.originalUrl_;
+      const domain = firstSlash != -1 ?
+          this.originalUrl_.substr(0, firstSlash) :
+          this.originalUrl_;
       return domain + url;
     }
 
     // Check for obvious relative paths.
-    var isRelative = false;
+    let isRelative = false;
     if (url.startsWith('.') || url.startsWith('\\'))
       isRelative = true;
 
@@ -244,19 +245,19 @@ Navigator.prototype = {
     // www.foo.com/bar -> http
     // foo.com/bar -> relative link
     if (!isRelative) {
-      var domainSeparatorIndex = url.indexOf('/');
-      var domainName = domainSeparatorIndex == -1 ?
+      const domainSeparatorIndex = url.indexOf('/');
+      const domainName = domainSeparatorIndex == -1 ?
           url :
           url.substr(0, domainSeparatorIndex);
-      var domainDotCount = (domainName.match(/\./g) || []).length;
+      const domainDotCount = (domainName.match(/\./g) || []).length;
       if (domainDotCount < 2)
         isRelative = true;
     }
 
     if (isRelative) {
-      var slashIndex = this.originalUrl_.lastIndexOf('/');
-      var path = slashIndex != -1 ? this.originalUrl_.substr(0, slashIndex) :
-                                    this.originalUrl_;
+      const slashIndex = this.originalUrl_.lastIndexOf('/');
+      const path = slashIndex != -1 ? this.originalUrl_.substr(0, slashIndex) :
+                                      this.originalUrl_;
       return path + '/' + url;
     }
 

chrome/browser/resources/pdf/open_pdf_params_parser.js

@@ -114,7 +114,7 @@ window.OpenPDFParamsParser = class {
       return params;
     }
 
-    for (let paramToken of paramTokens) {
+    for (const paramToken of paramTokens) {
       const keyValueSplit = paramToken.split('=');
       if (keyValueSplit.length != 2)
         continue;

chrome/browser/resources/pdf/pdf_fitting_type.js

@@ -8,7 +8,7 @@
  * Enumeration of page fitting types.
  * @enum {string}
  */
-var FittingType = {
+const FittingType = {
   NONE: 'none',
   FIT_TO_PAGE: 'fit-to-page',
   FIT_TO_WIDTH: 'fit-to-width',

chrome/browser/resources/pdf/pdf_scripting_api.js

@@ -9,7 +9,7 @@
  * @return {Event} A key event.
  */
 function DeserializeKeyEvent(dict) {
-  var e = document.createEvent('Event');
+  const e = document.createEvent('Event');
   e.initEvent('keydown', true, true);
   e.keyCode = dict.keyCode;
   e.code = dict.code;
@@ -43,7 +43,11 @@ function SerializeKeyEvent(event) {
  * has finished loading or failed to load.
  * @enum {string}
  */
-var LoadState = {LOADING: 'loading', SUCCESS: 'success', FAILED: 'failed'};
+const LoadState = {
+  LOADING: 'loading',
+  SUCCESS: 'success',
+  FAILED: 'failed'
+};
 
 /**
  * Create a new PDFScriptingAPI. This provides a scripting interface to
@@ -76,25 +80,27 @@ function PDFScriptingAPI(window, plugin) {
          *   viewportHeight: number
          * }}
          */
-        var viewportData = event.data;
+        const viewportData = event.data;
         if (this.viewportChangedCallback_)
           this.viewportChangedCallback_(
               viewportData.pageX, viewportData.pageY, viewportData.pageWidth,
               viewportData.viewportWidth, viewportData.viewportHeight);
         break;
-      case 'documentLoaded':
-        var data = /** @type {{load_state: LoadState}} */ (event.data);
+      case 'documentLoaded': {
+        const data = /** @type {{load_state: LoadState}} */ (event.data);
         this.loadState_ = data.load_state;
         if (this.loadCallback_)
           this.loadCallback_(this.loadState_ == LoadState.SUCCESS);
         break;
-      case 'getSelectedTextReply':
-        var data = /** @type {{selectedText: string}} */ (event.data);
+      }
+      case 'getSelectedTextReply': {
+        const data = /** @type {{selectedText: string}} */ (event.data);
         if (this.selectedTextCallback_) {
           this.selectedTextCallback_(data.selectedText);
           this.selectedTextCallback_ = null;
         }
         break;
+      }
       case 'sendKeyEvent':
         if (this.keyEventCallback_)
           this.keyEventCallback_(DeserializeKeyEvent(event.data.keyEvent));
@@ -257,8 +263,8 @@ PDFScriptingAPI.prototype = {
  * @return {HTMLIFrameElement} the iframe element containing the PDF viewer.
  */
 function PDFCreateOutOfProcessPlugin(src, baseUrl) {
-  var client = new PDFScriptingAPI(window, null);
-  var iframe = assertInstanceof(
+  const client = new PDFScriptingAPI(window, null);
+  const iframe = assertInstanceof(
       window.document.createElement('iframe'), HTMLIFrameElement);
   iframe.setAttribute('src', baseUrl + '/index.html?' + src);
   // Prevent the frame from being tab-focusable.

chrome/browser/resources/pdf/pdf_viewer.js

@@ -17,14 +17,14 @@ let SaveDataMessageData;
  * @return {number} Width of a scrollbar in pixels
  */
 function getScrollbarWidth() {
-  var div = document.createElement('div');
+  const div = document.createElement('div');
   div.style.visibility = 'hidden';
   div.style.overflow = 'scroll';
   div.style.width = '50px';
   div.style.height = '50px';
   div.style.position = 'absolute';
   document.body.appendChild(div);
-  var result = div.offsetWidth - div.clientWidth;
+  const result = div.offsetWidth - div.clientWidth;
   div.parentNode.removeChild(div);
   return result;
 }
@@ -37,9 +37,9 @@ function getScrollbarWidth() {
  */
 function getFilenameFromURL(url) {
   // Ignore the query and fragment.
-  var mainUrl = url.split(/#|\?/)[0];
-  var components = mainUrl.split(/\/|\\/);
-  var filename = components[components.length - 1];
+  const mainUrl = url.split(/#|\?/)[0];
+  const components = mainUrl.split(/\/|\\/);
+  const filename = components[components.length - 1];
   try {
     return decodeURIComponent(filename);
   } catch (e) {
@@ -142,7 +142,7 @@ function PDFViewer(browserApi) {
 
   // Parse open pdf parameters.
   this.paramsParser_ = new OpenPDFParamsParser(this.postMessage_.bind(this));
-  var toolbarEnabled =
+  const toolbarEnabled =
       this.paramsParser_.getUiUrlParams(this.originalUrl_).toolbar &&
       !this.isPrintPreview_;
 
@@ -164,10 +164,10 @@ function PDFViewer(browserApi) {
   }
 
   // Create the viewport.
-  var shortWindow = window.innerHeight < PDFViewer.TOOLBAR_WINDOW_MIN_HEIGHT;
-  var topToolbarHeight =
+  const shortWindow = window.innerHeight < PDFViewer.TOOLBAR_WINDOW_MIN_HEIGHT;
+  const topToolbarHeight =
       (toolbarEnabled) ? PDFViewer.MATERIAL_TOOLBAR_HEIGHT : 0;
-  var defaultZoom =
+  const defaultZoom =
       this.browserApi_.getZoomBehavior() == BrowserApi.ZoomBehavior.MANAGE ?
       this.browserApi_.getDefaultZoom() :
       1.0;
@@ -199,14 +199,14 @@ function PDFViewer(browserApi) {
   this.plugin_.setAttribute('src', this.originalUrl_);
   this.plugin_.setAttribute(
       'stream-url', this.browserApi_.getStreamInfo().streamUrl);
-  var headers = '';
-  for (var header in this.browserApi_.getStreamInfo().responseHeaders) {
+  let headers = '';
+  for (const header in this.browserApi_.getStreamInfo().responseHeaders) {
     headers += header + ': ' +
         this.browserApi_.getStreamInfo().responseHeaders[header] + '\n';
   }
   this.plugin_.setAttribute('headers', headers);
 
-  var backgroundColor = PDFViewer.DARK_BACKGROUND_COLOR;
+  const backgroundColor = PDFViewer.DARK_BACKGROUND_COLOR;
   this.plugin_.setAttribute('background-color', backgroundColor);
   this.plugin_.setAttribute('top-toolbar-height', topToolbarHeight);
   this.plugin_.setAttribute('javascript', this.javascript_);
@@ -266,7 +266,7 @@ function PDFViewer(browserApi) {
   });
 
   document.body.addEventListener('navigate', e => {
-    var disposition = e.detail.newtab ?
+    const disposition = e.detail.newtab ?
         Navigator.WindowOpenDisposition.NEW_BACKGROUND_TAB :
         Navigator.WindowOpenDisposition.CURRENT_TAB;
     this.navigator_.navigate(e.detail.uri, disposition);
@@ -296,7 +296,7 @@ function PDFViewer(browserApi) {
   document.addEventListener(
       'contextmenu', this.handleContextMenuEvent_.bind(this));
 
-  var tabId = this.browserApi_.getStreamInfo().tabId;
+  const tabId = this.browserApi_.getStreamInfo().tabId;
   this.navigator_ = new Navigator(
       this.originalUrl_, this.viewport_, this.paramsParser_,
       new NavigatorDelegate(tabId));
@@ -316,16 +316,16 @@ PDFViewer.prototype = {
    * @private
    */
   handleKeyEvent_: function(e) {
-    var position = this.viewport_.position;
+    const position = this.viewport_.position;
     // Certain scroll events may be sent from outside of the extension.
-    var fromScriptingAPI = e.fromScriptingAPI;
+    const fromScriptingAPI = e.fromScriptingAPI;
 
     if (shouldIgnoreKeyEvents(document.activeElement) || e.defaultPrevented)
       return;
 
     this.toolbarManager_.hideToolbarsAfterTimeout(e);
 
-    var pageUpHandler = () => {
+    const pageUpHandler = () => {
       // Go to the previous page if we are fit-to-page or fit-to-height.
       if (this.viewport_.isPagedMode()) {
         this.viewport_.goToPage(this.viewport_.getMostVisiblePage() - 1);
@@ -336,7 +336,7 @@ PDFViewer.prototype = {
         this.viewport.position = position;
       }
     };
-    var pageDownHandler = () => {
+    const pageDownHandler = () => {
       // Go to the next page if we are fit-to-page or fit-to-height.
       if (this.viewport_.isPagedMode()) {
         this.viewport_.goToPage(this.viewport_.getMostVisiblePage() + 1);
@@ -569,8 +569,8 @@ PDFViewer.prototype = {
       this.isUserInitiatedEvent_ = false;
       this.zoomToolbar_.forceFit(params.view);
       if (params.viewPosition) {
-        var zoomedPositionShift = params.viewPosition * this.viewport_.zoom;
-        var currentViewportPosition = this.viewport_.position;
+        const zoomedPositionShift = params.viewPosition * this.viewport_.zoom;
+        const currentViewportPosition = this.viewport_.position;
         if (params.view == FittingType.FIT_TO_WIDTH)
           currentViewportPosition.y += zoomedPositionShift;
         else if (params.view == FittingType.FIT_TO_HEIGHT)
@@ -708,7 +708,7 @@ PDFViewer.prototype = {
         }
         break;
       case 'email':
-        var href = 'mailto:' + message.data.to + '?cc=' + message.data.cc +
+        const href = 'mailto:' + message.data.to + '?cc=' + message.data.cc +
             '&bcc=' + message.data.bcc + '&subject=' + message.data.subject +
             '&body=' + message.data.body;
         window.location.href = href;
@@ -837,9 +837,9 @@ PDFViewer.prototype = {
     this.postMessage_({type: 'stopScrolling'});
 
     if (this.viewport_.pinchPhase == Viewport.PinchPhase.PINCH_START) {
-      var position = this.viewport_.position;
-      var zoom = this.viewport_.zoom;
-      var pinchPhase = this.viewport_.pinchPhase;
+      const position = this.viewport_.position;
+      const zoom = this.viewport_.zoom;
+      const pinchPhase = this.viewport_.pinchPhase;
       this.postMessage_({
         type: 'viewport',
         userInitiated: true,
@@ -858,11 +858,11 @@ PDFViewer.prototype = {
    * @private
    */
   afterZoom_: function() {
-    var position = this.viewport_.position;
-    var zoom = this.viewport_.zoom;
-    var pinchVector = this.viewport_.pinchPanVector || {x: 0, y: 0};
-    var pinchCenter = this.viewport_.pinchCenter || {x: 0, y: 0};
-    var pinchPhase = this.viewport_.pinchPhase;
+    const position = this.viewport_.position;
+    const zoom = this.viewport_.zoom;
+    const pinchVector = this.viewport_.pinchPanVector || {x: 0, y: 0};
+    const pinchCenter = this.viewport_.pinchCenter || {x: 0, y: 0};
+    const pinchPhase = this.viewport_.pinchPhase;
 
     this.postMessage_({
       type: 'viewport',
@@ -947,10 +947,10 @@ PDFViewer.prototype = {
       return;
 
     // Offset the toolbar position so that it doesn't move if scrollbars appear.
-    var hasScrollbars = this.viewport_.documentHasScrollbars();
-    var scrollbarWidth = this.viewport_.scrollbarWidth;
-    var verticalScrollbarWidth = hasScrollbars.vertical ? scrollbarWidth : 0;
-    var horizontalScrollbarWidth =
+    const hasScrollbars = this.viewport_.documentHasScrollbars();
+    const scrollbarWidth = this.viewport_.scrollbarWidth;
+    const verticalScrollbarWidth = hasScrollbars.vertical ? scrollbarWidth : 0;
+    const horizontalScrollbarWidth =
         hasScrollbars.horizontal ? scrollbarWidth : 0;
 
     // Shift the zoom toolbar to the left by half a scrollbar width. This
@@ -970,7 +970,7 @@ PDFViewer.prototype = {
     this.zoomToolbar_.style.bottom = -horizontalScrollbarWidth + 'px';
 
     // Update the page indicator.
-    var visiblePage = this.viewport_.getMostVisiblePage();
+    const visiblePage = this.viewport_.getMostVisiblePage();
 
     if (this.toolbar_)
       this.toolbar_.pageNo = visiblePage + 1;
@@ -986,8 +986,8 @@ PDFViewer.prototype = {
       }
     }
 
-    var visiblePageDimensions = this.viewport_.getPageScreenRect(visiblePage);
-    var size = this.viewport_.size;
+    const visiblePageDimensions = this.viewport_.getPageScreenRect(visiblePage);
+    const size = this.viewport_.size;
     this.sendScriptingMessage_({
       type: 'viewport',
       pageX: visiblePageDimensions.x,
@@ -1062,10 +1062,10 @@ PDFViewer.prototype = {
         this.lastViewportPosition_ = this.viewport_.position;
 
         // TODO(raymes): Disable these properly in the plugin.
-        var printButton = $('print-button');
+        const printButton = $('print-button');
         if (printButton)
           printButton.parentNode.removeChild(printButton);
-        var saveButton = $('save-button');
+        const saveButton = $('save-button');
         if (saveButton)
           saveButton.parentNode.removeChild(saveButton);
 
@@ -1085,7 +1085,7 @@ PDFViewer.prototype = {
         this.handleKeyEvent_(DeserializeKeyEvent(message.data.keyEvent));
         return true;
       case 'scrollPosition':
-        var position = this.viewport_.position;
+        const position = this.viewport_.position;
         position.y += message.data.y;
         position.x += message.data.x;
         this.viewport.position = position;
@@ -1104,7 +1104,7 @@ PDFViewer.prototype = {
    */
   sendScriptingMessage_: function(message) {
     if (this.parentWindow_ && this.parentOrigin_) {
-      var targetOrigin;
+      let targetOrigin;
       // Only send data back to the embedder if it is from the same origin,
       // unless we're sending it to ourselves (which could happen in the case
       // of tests). We also allow documentLoaded messages through as this won't

chrome/browser/resources/pdf/toolbar_manager.js

@@ -5,20 +5,20 @@
 'use strict';
 
 /** Idle time in ms before the UI is hidden. */
-var HIDE_TIMEOUT = 2000;
+const HIDE_TIMEOUT = 2000;
 /** Time in ms after force hide before toolbar is shown again. */
-var FORCE_HIDE_TIMEOUT = 1000;
+const FORCE_HIDE_TIMEOUT = 1000;
 /**
  * Velocity required in a mousemove to reveal the UI (pixels/ms). This is
  * intended to be high enough that a fast flick of the mouse is required to
  * reach it.
  */
-var SHOW_VELOCITY = 10;
+const SHOW_VELOCITY = 10;
 /** Distance from the top of the screen required to reveal the toolbars. */
-var TOP_TOOLBAR_REVEAL_DISTANCE = 100;
+const TOP_TOOLBAR_REVEAL_DISTANCE = 100;
 /** Distance from the bottom-right of the screen required to reveal toolbars. */
-var SIDE_TOOLBAR_REVEAL_DISTANCE_RIGHT = 150;
-var SIDE_TOOLBAR_REVEAL_DISTANCE_BOTTOM = 250;
+const SIDE_TOOLBAR_REVEAL_DISTANCE_RIGHT = 150;
+const SIDE_TOOLBAR_REVEAL_DISTANCE_BOTTOM = 250;
 
 
 
@@ -37,10 +37,11 @@ function isMouseNearTopToolbar(e) {
  * screen.
  */
 function isMouseNearSideToolbar(e, window) {
-  var atSide = e.x > window.innerWidth - SIDE_TOOLBAR_REVEAL_DISTANCE_RIGHT;
+  let atSide = e.x > window.innerWidth - SIDE_TOOLBAR_REVEAL_DISTANCE_RIGHT;
   if (isRTL())
     atSide = e.x < SIDE_TOOLBAR_REVEAL_DISTANCE_RIGHT;
-  var atBottom = e.y > window.innerHeight - SIDE_TOOLBAR_REVEAL_DISTANCE_BOTTOM;
+  const atBottom =
+      e.y > window.innerHeight - SIDE_TOOLBAR_REVEAL_DISTANCE_BOTTOM;
   return atSide && atBottom;
 }
 
@@ -80,7 +81,7 @@ ToolbarManager.prototype = {
     this.isMouseNearSideToolbar_ = isMouseNearSideToolbar(e, this.window_);
 
     this.keyboardNavigationActive = false;
-    var touchInteractionActive =
+    const touchInteractionActive =
         (e.sourceCapabilities && e.sourceCapabilities.firesTouchEvents);
 
     // Allow the top toolbar to be shown if the mouse moves away from the side
@@ -123,10 +124,10 @@ ToolbarManager.prototype = {
       if (this.lastMovementTimestamp == null) {
         this.lastMovementTimestamp = this.getCurrentTimestamp_();
       } else {
-        var movement =
+        const movement =
             Math.sqrt(e.movementX * e.movementX + e.movementY * e.movementY);
-        var newTime = this.getCurrentTimestamp_();
-        var interval = newTime - this.lastMovementTimestamp;
+        const newTime = this.getCurrentTimestamp_();
+        const interval = newTime - this.lastMovementTimestamp;
         this.lastMovementTimestamp = newTime;
 
         if (interval != 0)
@@ -250,7 +251,8 @@ ToolbarManager.prototype = {
   resizeDropdowns_: function() {
     if (!this.toolbar_)
       return;
-    var lowerBound = this.window_.innerHeight - this.zoomToolbar_.clientHeight;
+    const lowerBound =
+        this.window_.innerHeight - this.zoomToolbar_.clientHeight;
     this.toolbar_.setDropdownLowerBound(lowerBound);
   }
 };

chrome/browser/resources/pdf/viewport.js

@@ -54,7 +54,7 @@ function vectorDelta(p1, p2) {
 }
 
 function frameToPluginCoordinate(coordinateInFrame) {
-  var container = $('plugin');
+  const container = $('plugin');
   return {
     x: coordinateInFrame.x - container.getBoundingClientRect().left,
     y: coordinateInFrame.y - container.getBoundingClientRect().top
@@ -263,7 +263,7 @@ Viewport.prototype = {
    * @private
    */
   documentNeedsScrollbars_: function(zoom) {
-    var zoomedDimensions = this.getZoomedDocumentDimensions_(zoom);
+    const zoomedDimensions = this.getZoomedDocumentDimensions_(zoom);
     if (!zoomedDimensions) {
       return {horizontal: false, vertical: false};
     }
@@ -299,7 +299,7 @@ Viewport.prototype = {
    * @private
    */
   contentSizeChanged_: function() {
-    var zoomedDimensions = this.getZoomedDocumentDimensions_(this.zoom);
+    const zoomedDimensions = this.getZoomedDocumentDimensions_(this.zoom);
     if (zoomedDimensions) {
       this.sizer_.style.width = zoomedDimensions.width + 'px';
       this.sizer_.style.height =
@@ -368,9 +368,10 @@ Viewport.prototype = {
    * @type {Object} the size of the viewport excluding scrollbars.
    */
   get size() {
-    var needsScrollbars = this.documentNeedsScrollbars_(this.zoom);
-    var scrollbarWidth = needsScrollbars.vertical ? this.scrollbarWidth_ : 0;
-    var scrollbarHeight = needsScrollbars.horizontal ? this.scrollbarWidth_ : 0;
+    const needsScrollbars = this.documentNeedsScrollbars_(this.zoom);
+    const scrollbarWidth = needsScrollbars.vertical ? this.scrollbarWidth_ : 0;
+    const scrollbarHeight =
+        needsScrollbars.horizontal ? this.scrollbarWidth_ : 0;
     return {
       width: this.window_.innerWidth - scrollbarWidth,
       height: this.window_.innerHeight - scrollbarHeight
@@ -446,7 +447,7 @@ Viewport.prototype = {
           'Viewport.mightZoom_.');
     }
     // Record the scroll position (relative to the top-left of the window).
-    var currentScrollPos = {
+    const currentScrollPos = {
       x: this.position.x / this.zoom,
       y: this.position.y / this.zoom
     };
@@ -475,14 +476,14 @@ Viewport.prototype = {
             'Viewport.mightZoom_.');
     this.internalZoom_ = Viewport.clampZoom(this.internalZoom_ * scaleDelta);
 
-    var newCenterInContent = this.frameToContent(center);
-    var delta = {
+    const newCenterInContent = this.frameToContent(center);
+    const delta = {
       x: (newCenterInContent.x - this.oldCenterInContent.x),
       y: (newCenterInContent.y - this.oldCenterInContent.y)
     };
 
     // Record the scroll position (relative to the pinch center).
-    var currentScrollPos = {
+    const currentScrollPos = {
       x: this.position.x - delta.x * this.zoom,
       y: this.position.y - delta.y * this.zoom
     };
@@ -530,8 +531,8 @@ Viewport.prototype = {
   updateZoomFromBrowserChange: function(oldBrowserZoom) {
     this.mightZoom_(() => {
       // Record the scroll position (relative to the top-left of the window).
-      var oldZoom = oldBrowserZoom * this.internalZoom_;
-      var currentScrollPos = {
+      const oldZoom = oldBrowserZoom * this.internalZoom_;
+      const currentScrollPos = {
         x: this.position.x / oldZoom,
         y: this.position.y / oldZoom
       };
@@ -567,18 +568,18 @@ Viewport.prototype = {
    * @private
    */
   getPageAtY_: function(y) {
-    var min = 0;
-    var max = this.pageDimensions_.length - 1;
+    let min = 0;
+    let max = this.pageDimensions_.length - 1;
     while (max >= min) {
-      var page = Math.floor(min + ((max - min) / 2));
+      const page = Math.floor(min + ((max - min) / 2));
       // There might be a gap between the pages, in which case use the bottom
       // of the previous page as the top for finding the page.
-      var top = 0;
+      let top = 0;
       if (page > 0) {
         top = this.pageDimensions_[page - 1].y +
             this.pageDimensions_[page - 1].height;
       }
-      var bottom =
+      const bottom =
           this.pageDimensions_[page].y + this.pageDimensions_[page].height;
 
       if (top <= y && bottom > y)
@@ -599,21 +600,21 @@ Viewport.prototype = {
    * @return {number} the index of the most visible page.
    */
   getMostVisiblePage: function() {
-    var firstVisiblePage = this.getPageAtY_(this.position.y / this.zoom);
+    const firstVisiblePage = this.getPageAtY_(this.position.y / this.zoom);
     if (firstVisiblePage == this.pageDimensions_.length - 1)
       return firstVisiblePage;
 
-    var viewportRect = {
+    const viewportRect = {
       x: this.position.x / this.zoom,
       y: this.position.y / this.zoom,
       width: this.size.width / this.zoom,
       height: this.size.height / this.zoom
     };
-    var firstVisiblePageVisibility =
+    const firstVisiblePageVisibility =
         getIntersectionHeight(
             this.pageDimensions_[firstVisiblePage], viewportRect) /
         this.pageDimensions_[firstVisiblePage].height;
-    var nextPageVisibility =
+    const nextPageVisibility =
         getIntersectionHeight(
             this.pageDimensions_[firstVisiblePage + 1], viewportRect) /
         this.pageDimensions_[firstVisiblePage + 1].height;
@@ -642,21 +643,21 @@ Viewport.prototype = {
             'true.');
 
     // First compute the zoom without scrollbars.
-    var zoom = this.computeFittingZoomGivenDimensions_(
+    let zoom = this.computeFittingZoomGivenDimensions_(
         fitWidth, fitHeight, this.window_.innerWidth, this.window_.innerHeight,
         pageDimensions.width, pageDimensions.height);
 
     // Check if there needs to be any scrollbars.
-    var needsScrollbars = this.documentNeedsScrollbars_(zoom);
+    const needsScrollbars = this.documentNeedsScrollbars_(zoom);
 
     // If the document fits, just return the zoom.
     if (!needsScrollbars.horizontal && !needsScrollbars.vertical)
       return zoom;
 
-    var zoomedDimensions = this.getZoomedDocumentDimensions_(zoom);
+    const zoomedDimensions = this.getZoomedDocumentDimensions_(zoom);
 
     // Check if adding a scrollbar will result in needing the other scrollbar.
-    var scrollbarWidth = this.scrollbarWidth_;
+    const scrollbarWidth = this.scrollbarWidth_;
     if (needsScrollbars.horizontal &&
         zoomedDimensions.height > this.window_.innerHeight - scrollbarWidth) {
       needsScrollbars.vertical = true;
@@ -667,7 +668,7 @@ Viewport.prototype = {
     }
 
     // Compute available window space.
-    var windowWithScrollbars = {
+    const windowWithScrollbars = {
       width: this.window_.innerWidth,
       height: this.window_.innerHeight
     };
@@ -703,8 +704,8 @@ Viewport.prototype = {
   computeFittingZoomGivenDimensions_: function(
       fitWidth, fitHeight, windowWidth, windowHeight, pageWidth, pageHeight) {
     // Assumes at least one of {fitWidth, fitHeight} is set.
-    var zoomWidth;
-    var zoomHeight;
+    let zoomWidth;
+    let zoomHeight;
 
     if (fitWidth)
       zoomWidth = windowWidth / pageWidth;
@@ -712,7 +713,7 @@ Viewport.prototype = {
     if (fitHeight)
       zoomHeight = windowHeight / pageHeight;
 
-    var zoom;
+    let zoom;
     if (!fitWidth && fitHeight) {
       zoom = zoomHeight;
     } else if (fitWidth && !fitHeight) {
@@ -754,10 +755,10 @@ Viewport.prototype = {
       this.fittingType_ = FittingType.FIT_TO_HEIGHT;
       if (!this.documentDimensions_)
         return;
-      var page = this.getMostVisiblePage();
+      const page = this.getMostVisiblePage();
       // When computing fit-to-height, the maximum height of the current page
       // is used.
-      var dimensions = {
+      const dimensions = {
         width: 0,
         height: this.pageDimensions_[page].height,
       };
@@ -789,9 +790,9 @@ Viewport.prototype = {
       this.fittingType_ = FittingType.FIT_TO_PAGE;
       if (!this.documentDimensions_)
         return;
-      var page = this.getMostVisiblePage();
+      const page = this.getMostVisiblePage();
       // Fit to the current page's height and the widest page's width.
-      var dimensions = {
+      const dimensions = {
         width: this.documentDimensions_.width,
         height: this.pageDimensions_[page].height,
       };
@@ -832,8 +833,8 @@ Viewport.prototype = {
   zoomOut: function() {
     this.mightZoom_(() => {
       this.fittingType_ = FittingType.NONE;
-      var nextZoom = Viewport.ZOOM_FACTORS[0];
-      for (var i = 0; i < Viewport.ZOOM_FACTORS.length; i++) {
+      let nextZoom = Viewport.ZOOM_FACTORS[0];
+      for (let i = 0; i < Viewport.ZOOM_FACTORS.length; i++) {
         if (Viewport.ZOOM_FACTORS[i] < this.internalZoom_)
           nextZoom = Viewport.ZOOM_FACTORS[i];
       }
@@ -848,8 +849,8 @@ Viewport.prototype = {
   zoomIn: function() {
     this.mightZoom_(() => {
       this.fittingType_ = FittingType.NONE;
-      var nextZoom = Viewport.ZOOM_FACTORS[Viewport.ZOOM_FACTORS.length - 1];
-      for (var i = Viewport.ZOOM_FACTORS.length - 1; i >= 0; i--) {
+      let nextZoom = Viewport.ZOOM_FACTORS[Viewport.ZOOM_FACTORS.length - 1];
+      for (let i = Viewport.ZOOM_FACTORS.length - 1; i >= 0; i--) {
         if (Viewport.ZOOM_FACTORS[i] > this.internalZoom_)
           nextZoom = Viewport.ZOOM_FACTORS[i];
       }
@@ -869,11 +870,11 @@ Viewport.prototype = {
           Viewport.PinchPhase.PINCH_UPDATE_ZOOM_OUT :
           Viewport.PinchPhase.PINCH_UPDATE_ZOOM_IN;
 
-      var scaleDelta = e.startScaleRatio / this.prevScale_;
+      const scaleDelta = e.startScaleRatio / this.prevScale_;
       this.pinchPanVector_ =
           vectorDelta(e.center, this.firstPinchCenterInFrame_);
 
-      var needsScrollbars =
+      const needsScrollbars =
           this.documentNeedsScrollbars_(this.zoomManager_.applyBrowserZoom(
               Viewport.clampZoom(this.internalZoom_ * scaleDelta)));
 
@@ -908,7 +909,7 @@ Viewport.prototype = {
     this.oldCenterInContent =
         this.frameToContent(frameToPluginCoordinate(e.center));
 
-    var needsScrollbars = this.documentNeedsScrollbars_(this.zoom);
+    const needsScrollbars = this.documentNeedsScrollbars_(this.zoom);
     this.keepContentCentered_ = !needsScrollbars.horizontal;
     // We keep track of begining of the pinch.
     // By doing so we will be able to compute the pan distance.
@@ -918,7 +919,7 @@ Viewport.prototype = {
   pinchZoomEnd: function(e) {
     this.mightZoom_(() => {
       this.pinchPhase_ = Viewport.PinchPhase.PINCH_END;
-      var scaleDelta = e.startScaleRatio / this.prevScale_;
+      const scaleDelta = e.startScaleRatio / this.prevScale_;
       this.pinchCenter_ = e.center;
 
       this.setPinchZoomInternal_(scaleDelta, frameToPluginCoordinate(e.center));
@@ -955,8 +956,8 @@ Viewport.prototype = {
         page = 0;
       if (page >= this.pageDimensions_.length)
         page = this.pageDimensions_.length - 1;
-      var dimensions = this.pageDimensions_[page];
-      var toolbarOffset = 0;
+      const dimensions = this.pageDimensions_[page];
+      let toolbarOffset = 0;
       // Unless we're in fit to page or fit to height mode, scroll above the
       // page by |this.topToolbarHeight_| so that the toolbar isn't covering it
       // initially.
@@ -977,7 +978,7 @@ Viewport.prototype = {
    */
   setDocumentDimensions: function(documentDimensions) {
     this.mightZoom_(() => {
-      var initialDimensions = !this.documentDimensions_;
+      const initialDimensions = !this.documentDimensions_;
       this.documentDimensions_ = documentDimensions;
       this.pageDimensions_ = this.documentDimensions_.pageDimensions;
       if (initialDimensions) {
@@ -1020,19 +1021,19 @@ Viewport.prototype = {
     if (page >= this.pageDimensions_.length)
       page = this.pageDimensions_.length - 1;
 
-    var pageDimensions = this.pageDimensions_[page];
+    const pageDimensions = this.pageDimensions_[page];
 
     // Compute the page dimensions minus the shadows.
-    var insetDimensions = this.getPageInsetDimensions(page);
+    const insetDimensions = this.getPageInsetDimensions(page);
 
     // Compute the x-coordinate of the page within the document.
     // TODO(raymes): This should really be set when the PDF plugin passes the
     // page coordinates, but it isn't yet.
-    var x = (this.documentDimensions_.width - pageDimensions.width) / 2 +
+    const x = (this.documentDimensions_.width - pageDimensions.width) / 2 +
         Viewport.PAGE_SHADOW.left;
     // Compute the space on the left of the document if the document fits
     // completely in the screen.
-    var spaceOnLeft =
+    let spaceOnLeft =
         (this.size.width - this.documentDimensions_.width * this.zoom) / 2;
     spaceOnLeft = Math.max(spaceOnLeft, 0);
 

chrome/browser/resources/pdf/viewport_scroller.js

@@ -74,9 +74,9 @@ ViewportScroller.prototype = {
    * @private
    */
   dragScrollPage_: function() {
-    var position = this.viewport_.position;
-    var currentFrameTime = Date.now();
-    var timeAdjustment = (currentFrameTime - this.lastFrameTime_) /
+    const position = this.viewport_.position;
+    const currentFrameTime = Date.now();
+    const timeAdjustment = (currentFrameTime - this.lastFrameTime_) /
         ViewportScroller.DRAG_TIMER_INTERVAL_MS_;
     position.y += (this.scrollVelocity_.y * timeAdjustment);
     position.x += (this.scrollVelocity_.x * timeAdjustment);
@@ -93,13 +93,13 @@ ViewportScroller.prototype = {
    * @private
    */
   calculateVelocity_: function(event) {
-    var x =
+    const x =
         Math.min(
             Math.max(
                 -event.offsetX, event.offsetX - this.plugin_.offsetWidth, 0),
             ViewportScroller.MAX_DRAG_SCROLL_DISTANCE_) *
         Math.sign(event.offsetX);
-    var y =
+    const y =
         Math.min(
             Math.max(
                 -event.offsetY, event.offsetY - this.plugin_.offsetHeight, 0),

chrome/browser/resources/pdf/zoom_manager.js

@@ -84,7 +84,7 @@ class ZoomManager {
    * @param {number} b The second number.
    */
   floatingPointEquals(a, b) {
-    let MIN_ZOOM_DELTA = 0.01;
+    const MIN_ZOOM_DELTA = 0.01;
     // If the zoom level is close enough to the current zoom level, don't
     // change it. This avoids us getting into an infinite loop of zoom changes
     // due to floating point error.
@@ -147,7 +147,7 @@ class ActiveZoomManager extends ZoomManager {
     if (this.changingBrowserZoom_)
       return;
 
-    let zoom = this.viewport_.zoom;
+    const zoom = this.viewport_.zoom;
     if (this.floatingPointEquals(this.browserZoom_, zoom))
       return;
 
@@ -200,7 +200,7 @@ class EmbeddedZoomManager extends ZoomManager {
    * @param {number} newZoom the new browser zoom level.
    */
   onBrowserZoomChange(newZoom) {
-    let oldZoom = this.browserZoom_;
+    const oldZoom = this.browserZoom_;
     this.browserZoom_ = newZoom;
     this.viewport_.updateZoomFromBrowserChange(oldZoom);
   }