pdf: Use assert.js instead of `new Error`

Change-Id: I851cd8143482f383f3c1d16c960085ff3911c348
Reviewed-on: https://chromium-review.googlesource.com/c/1377954
Commit-Queue: dstockwell <dstockwell@chromium.org>
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#619361}

chrome/browser/resources/pdf/BUILD.gn

@@ -18,6 +18,9 @@ group("closure_compile") {
 }
 
 js_library("browser_api") {
+  deps = [
+    "//ui/webui/resources/js:assert",
+  ]
   externs_list = [
     "$externs_path/chrome_extensions.js",
     "$externs_path/mime_handler_private.js",

chrome/browser/resources/pdf/browser_api.js

@@ -102,8 +102,9 @@ class BrowserApi {
    *     has been updated.
    */
   setZoom(zoom) {
-    if (this.zoomBehavior_ != BrowserApi.ZoomBehavior.MANAGE)
-      return Promise.reject(new Error('Viewer does not manage browser zoom.'));
+    assert(
+        this.zoomBehavior_ == BrowserApi.ZoomBehavior.MANAGE,
+        'Viewer does not manage browser zoom.');
     return new Promise((resolve, reject) => {
       chrome.tabs.setZoom(this.streamInfo_.tabId, zoom, resolve);
     });

chrome/browser/resources/pdf/index.html

@@ -37,9 +37,10 @@
 <script src="zoom_manager.js"></script>
 <script src="gesture_detector.js"></script>
 <script src="pdf_scripting_api.js"></script>
-<link rel="import" href="chrome://resources/html/load_time_data.html">
-<link rel="import" href="chrome://resources/html/promise_resolver.html">
-<link rel="import" href="chrome://resources/html/util.html">
+<script src="chrome://resources/js/assert.js"></script>
+<script src="chrome://resources/js/load_time_data.js"></script>
+<script src="chrome://resources/js/util.js"></script>
+<script src="chrome://resources/js/promise_resolver.js"></script>
 <script src="browser_api.js"></script>
 <script src="metrics.js"></script>
 <script src="pdf_viewer.js"></script>

chrome/browser/resources/pdf/pdf_viewer.js

@@ -483,11 +483,7 @@ PDFViewer.prototype = {
   annotationModeChanged_: async function(e) {
     const annotationMode = e.detail.value;
     if (annotationMode) {
-      // TODO(dstockwell): add assert lib and replace this with assert
-      if (this.currentController_ != this.pluginController_) {
-        throw new Error(
-            'Plugin controller is not current, cannot enter annotation mode');
-      }
+      assert(this.currentController_ == this.pluginController_);
       // Enter annotation mode.
       // TODO(dstockwell): set plugin read-only, begin transition
       this.updateProgress(0);
@@ -501,11 +497,7 @@ PDFViewer.prototype = {
       this.updateProgress(100);
     } else {
       // Exit annotation mode.
-      // TODO(dstockwell): add assert lib and replace this with assert
-      if (this.currentController_ != this.inkController_) {
-        throw new Error(
-            'Ink controller is not current, cannot exit annotation mode');
-      }
+      assert(this.currentController_ == this.inkController_);
       // TODO(dstockwell): set ink read-only, begin transition
       this.updateProgress(0);
       // This runs separately to allow other consumers of `loaded` to queue
@@ -625,18 +617,17 @@ PDFViewer.prototype = {
     if (this.loadState_ == loadState) {
       return;
     }
-    if ((loadState == LoadState.SUCCESS || loadState == LoadState.FAILURE) &&
-        this.loadState_ != LoadState.LOADING) {
-      throw new Error('Internal error: invalid loadState transition.');
-    }
-    this.loadState_ = loadState;
     if (loadState == LoadState.SUCCESS) {
+      assert(this.loadState_ == LoadState.LOADING);
       this.loaded_.resolve();
     } else if (loadState == LoadState.FAILED) {
+      assert(this.loadState_ == LoadState.LOADING);
       this.loaded_.reject();
     } else {
+      assert(loadState == LoadState.LOADING);
       this.loaded_ = new PromiseResolver();
     }
+    this.loadState_ = loadState;
   },
 
   /**
@@ -716,9 +707,7 @@ PDFViewer.prototype = {
    * @private
    */
   setUserInitiated_: function(userInitiated) {
-    if (this.isUserInitiatedEvent_ == userInitiated) {
-      throw new Error('Trying to set user initiated to current value.');
-    }
+    assert(this.isUserInitiatedEvent_ != userInitiated);
     this.isUserInitiatedEvent_ = userInitiated;
   },
 
@@ -1403,8 +1392,7 @@ class PluginController extends ContentController {
         break;
       case 'consumeSaveToken':
         const resolve = this.pendingTokens_.get(message.data.token);
-        if (!this.pendingTokens_.delete(message.data.token))
-          throw new Error('Internal error: save token not found.');
+        assert(this.pendingTokens_.delete(message.data.token));
         resolve(null);
         break;
     }
@@ -1417,15 +1405,14 @@ class PluginController extends ContentController {
    * @private
    */
   saveData_(messageData) {
-    if (!(loadTimeData.getBoolean('pdfFormSaveEnabled') ||
-          loadTimeData.getBoolean('pdfAnnotationsEnabled')))
-      throw new Error('Internal error: save not enabled.');
+    assert(
+        loadTimeData.getBoolean('pdfFormSaveEnabled') ||
+        loadTimeData.getBoolean('pdfAnnotationsEnabled'));
 
     // Verify a token that was created by this instance is included to avoid
     // being spammed.
     const resolver = this.pendingTokens_.get(messageData.token);
-    if (!this.pendingTokens_.delete(messageData.token))
-      throw new Error('Internal error: save token not found, abort save.');
+    assert(this.pendingTokens_.delete(messageData.token));
 
     if (!messageData.dataToSave) {
       resolver.reject();
@@ -1440,13 +1427,13 @@ class PluginController extends ContentController {
 
     const buffer = messageData.dataToSave;
     const bufView = new Uint8Array(buffer);
-    if (bufView.length > MAX_FILE_SIZE)
-      throw new Error(`File too large to be saved: ${bufView.length} bytes.`);
-    if (bufView.length < MIN_FILE_SIZE ||
-        String.fromCharCode(bufView[0], bufView[1], bufView[2], bufView[3]) !=
-            '%PDF') {
-      throw new Error('Not a PDF file.');
-    }
+    assert(
+        bufView.length <= MAX_FILE_SIZE,
+        `File too large to be saved: ${bufView.length} bytes.`);
+    assert(bufView.length >= MIN_FILE_SIZE);
+    assert(
+        String.fromCharCode(bufView[0], bufView[1], bufView[2], bufView[3]) ==
+        '%PDF');
 
     resolver.resolve(messageData);
   }

chrome/browser/resources/pdf/viewport.js

@@ -441,11 +441,10 @@ Viewport.prototype = {
    * @private
    */
   setZoomInternal_: function(newZoom) {
-    if (!this.allowedToChangeZoom_) {
-      throw new Error(
+    assert(
+        this.allowedToChangeZoom_,
         'Called Viewport.setZoomInternal_ without calling ' +
             'Viewport.mightZoom_.');
-    }
     // Record the scroll position (relative to the top-left of the window).
     const currentScrollPos = {
       x: this.position.x / this.zoom,