Record metrics for zoom in and zoom out actions inside PDF viewer.

Bug: 1039520
Change-Id: I34c324b776b0248a907f45d1a74b5d72d3cb59cf
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2203151
Commit-Queue: Hui Yingst <nigi@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Reviewed-by: Henrique Nakashima <hnakashima@chromium.org>
Cr-Commit-Position: refs/heads/master@{#769961}

chrome/browser/resources/pdf/metrics.js

@@ -35,6 +35,18 @@ export class PDFMetrics {
             PDFMetrics.UserAction.TWO_UP_VIEW_DISABLE);
   }
 
+  /**
+   * Records zoom in and zoom out actions.
+   *
+   * @param {boolean} isZoomIn True when the action is zooming in, false when
+   * the action is zooming out.
+   */
+  static recordZoomAction(isZoomIn) {
+    PDFMetrics.record(
+        isZoomIn ? PDFMetrics.UserAction.ZOOM_IN :
+                   PDFMetrics.UserAction.ZOOM_OUT);
+  }
+
   /**
    * Records the given action to chrome.metricsPrivate.
    *
@@ -169,7 +181,15 @@ PDFMetrics.UserAction = {
   TWO_UP_VIEW_DISABLE_FIRST: 37,
   TWO_UP_VIEW_DISABLE: 38,
 
-  NUMBER_OF_ACTIONS: 39,
+  /** Recorded when zoom in button is clicked. */
+  ZOOM_IN_FIRST: 39,
+  ZOOM_IN: 40,
+
+  /** Recorded when zoom out button is clicked. */
+  ZOOM_OUT_FIRST: 41,
+  ZOOM_OUT: 42,
+
+  NUMBER_OF_ACTIONS: 43,
 };
 
 // Map from UserAction to the 'FIRST' action. These metrics are recorded
@@ -252,4 +272,12 @@ PDFMetrics.firstMap_ = new Map([
     PDFMetrics.UserAction.TWO_UP_VIEW_DISABLE,
     PDFMetrics.UserAction.TWO_UP_VIEW_DISABLE_FIRST,
   ],
+  [
+    PDFMetrics.UserAction.ZOOM_IN,
+    PDFMetrics.UserAction.ZOOM_IN_FIRST,
+  ],
+  [
+    PDFMetrics.UserAction.ZOOM_OUT,
+    PDFMetrics.UserAction.ZOOM_OUT_FIRST,
+  ],
 ]);

chrome/browser/resources/pdf/pdf_viewer.js

@@ -339,10 +339,14 @@ export class PDFViewer {
         'two-up-view-changed',
         e => this.twoUpViewChanged_(
             /** @type {!CustomEvent<!TwoUpViewAction>} */ (e)));
-    this.zoomToolbar_.addEventListener(
-        'zoom-in', () => this.viewport_.zoomIn());
-    this.zoomToolbar_.addEventListener(
-        'zoom-out', () => this.viewport_.zoomOut());
+    this.zoomToolbar_.addEventListener('zoom-in', () => {
+      this.viewport_.zoomIn();
+      PDFMetrics.recordZoomAction(/*isZoomIn=*/ true);
+    });
+    this.zoomToolbar_.addEventListener('zoom-out', () => {
+      this.viewport_.zoomOut();
+      PDFMetrics.recordZoomAction(/*isZoomIn=*/ false);
+    });
 
     /** @private {!GestureDetector} */
     this.gestureDetector_ = new GestureDetector(assert($('content')));

chrome/test/data/pdf/metrics_test.js

@@ -105,6 +105,29 @@ chrome.test.runTests(function() {
       chrome.test.succeed();
     },
 
+    function testMetricsZoomAction() {
+      PDFMetrics.resetForTesting();
+
+      chrome.metricsPrivate = new MockMetricsPrivate();
+      PDFMetrics.record(PDFMetrics.UserAction.DOCUMENT_OPENED);
+      PDFMetrics.recordZoomAction(/*isZoomIn=*/ true);
+      PDFMetrics.recordZoomAction(/*isZoomIn=*/ false);
+      PDFMetrics.recordZoomAction(/*isZoomIn=*/ true);
+      PDFMetrics.recordZoomAction(/*isZoomIn=*/ false);
+      PDFMetrics.recordZoomAction(/*isZoomIn=*/ true);
+
+      chrome.test.assertEq(
+          {
+            [PDFMetrics.UserAction.DOCUMENT_OPENED]: 1,
+            [PDFMetrics.UserAction.ZOOM_IN_FIRST]: 1,
+            [PDFMetrics.UserAction.ZOOM_IN]: 3,
+            [PDFMetrics.UserAction.ZOOM_OUT_FIRST]: 1,
+            [PDFMetrics.UserAction.ZOOM_OUT]: 2
+          },
+          chrome.metricsPrivate.actionCounter);
+      chrome.test.succeed();
+    },
+
     function testMetricsBookmarks() {
       PDFMetrics.resetForTesting();
 

tools/metrics/histograms/enums.xml

@@ -9086,6 +9086,10 @@ histogram as enum -->
   <int value="36" label="TwoUpViewEnable"/>
   <int value="37" label="TwoUpViewDisableFirst"/>
   <int value="38" label="TwoUpViewDisable"/>
+  <int value="39" label="ZoomInFirst"/>
+  <int value="40" label="ZoomIn"/>
+  <int value="41" label="ZoomOutFirst"/>
+  <int value="42" label="ZoomOut"/>
 </enum>
 
 <enum name="ChromePDFViewerAnnotationType">