PDF Viewer: Register several listeners declaratively.

Previously the code was imperatively registering such listeners on
|document.body| which was unnecessary. Moreover, adding meaningful
type checking for such listeners, since previously they were lacking
type info.

Bug: None
Change-Id: I1041f0becf89d1f88b03a1ad2dc9ec9e85a99e4c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2304956
Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
Auto-Submit: dpapad <dpapad@chromium.org>
Reviewed-by: Rebekah Potter <rbpotter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#789722}

chrome/browser/resources/pdf/pdf_viewer.html

@@ -34,6 +34,10 @@
       ink-controller="[[inkController_]]"
       pdf-annotations-enabled="[[pdfAnnotationsEnabled_]]"
 </if>
+      on-change-page-and-xy="onChangePageAndXy_"
+      on-change-page="onChangePage_"
+      on-dropdown-opened="onDropdownOpened_"
+      on-navigate="onNavigate_"
       on-save="onToolbarSave_" on-print="onPrint_"
 <if expr="chromeos">
       on-annotation-mode-toggled="onAnnotationModeToggled_"
@@ -55,6 +59,8 @@
     ink-controller="[[inkController_]]"
     pdf-annotations-enabled="[[pdfAnnotationsEnabled_]]"
 </if>
+    on-change-page="onChangePage_"
+    on-dropdown-opened="onDropdownOpened_"
     on-fit-to-changed="onFitToChanged" on-zoom-in="onZoomIn"
     on-zoom-out="onZoomOut" on-rotate-left="rotateCounterclockwise"
 <if expr="chromeos">

chrome/browser/resources/pdf/pdf_viewer.js

@@ -318,33 +318,6 @@ export class PDFViewerElement extends PDFViewerBaseElement {
       this.getToolbar_().hidden = false;
     }
 
-    document.body.addEventListener('change-page', e => {
-      this.viewport.goToPage(e.detail.page);
-      if (e.detail.origin === 'bookmark') {
-        PDFMetrics.record(PDFMetrics.UserAction.FOLLOW_BOOKMARK);
-      } else if (e.detail.origin === 'pageselector') {
-        PDFMetrics.record(PDFMetrics.UserAction.PAGE_SELECTOR_NAVIGATE);
-      }
-    });
-
-    document.body.addEventListener('change-page-and-xy', e => {
-      const point = this.viewport.convertPageToScreen(e.detail.page, e.detail);
-      this.goToPageAndXY_(e.detail.origin, e.detail.page, point);
-    });
-
-    document.body.addEventListener('navigate', e => {
-      const disposition = e.detail.newtab ?
-          PdfNavigator.WindowOpenDisposition.NEW_BACKGROUND_TAB :
-          PdfNavigator.WindowOpenDisposition.CURRENT_TAB;
-      this.navigator_.navigate(e.detail.uri, disposition);
-    });
-
-    document.body.addEventListener('dropdown-opened', e => {
-      if (e.detail === 'bookmarks') {
-        PDFMetrics.record(PDFMetrics.UserAction.OPEN_BOOKMARKS_PANEL);
-      }
-    });
-
     if (!this.pdfViewerUpdateEnabled_) {
       this.toolbarManager_ = new ToolbarManager(
           window, this.getToolbar_(), this.getZoomToolbar_());
@@ -835,6 +808,50 @@ export class PDFViewerElement extends PDFViewerBaseElement {
     this.save_(e.detail);
   }
 
+  /**
+   * @param {!CustomEvent<!{page: number, origin: string}>} e
+   * @private
+   */
+  onChangePage_(e) {
+    this.viewport.goToPage(e.detail.page);
+    if (e.detail.origin === 'bookmark') {
+      PDFMetrics.record(PDFMetrics.UserAction.FOLLOW_BOOKMARK);
+    } else if (e.detail.origin === 'pageselector') {
+      PDFMetrics.record(PDFMetrics.UserAction.PAGE_SELECTOR_NAVIGATE);
+    }
+  }
+
+  /**
+   * @param {!CustomEvent<!{
+   *   page: number, origin: string, x: number, y: number}>} e
+   * @private
+   */
+  onChangePageAndXy_(e) {
+    const point = this.viewport.convertPageToScreen(e.detail.page, e.detail);
+    this.goToPageAndXY_(e.detail.origin, e.detail.page, point);
+  }
+
+  /**
+   * @param {!CustomEvent<string>} e
+   * @private
+   */
+  onDropdownOpened_(e) {
+    if (e.detail === 'bookmarks') {
+      PDFMetrics.record(PDFMetrics.UserAction.OPEN_BOOKMARKS_PANEL);
+    }
+  }
+
+  /**
+   * @param {!CustomEvent<!{newtab: boolean, uri: string}>} e
+   * @private
+   */
+  onNavigate_(e) {
+    const disposition = e.detail.newtab ?
+        PdfNavigator.WindowOpenDisposition.NEW_BACKGROUND_TAB :
+        PdfNavigator.WindowOpenDisposition.CURRENT_TAB;
+    this.navigator_.navigate(e.detail.uri, disposition);
+  }
+
   /**
    * Saves the current PDF document to disk.
    * @param {SaveRequestType} requestType The type of save request.