[PageZoom] Add UKM for new zoom value on slider dismissal

This CL adds logging for UKM at the same point when existing UMA
is logged: at dismissal of the Page Zoom slider if the user
changed the slider value before dismissal.

See UKM Collection in the Privacy Considerations section at
go/clank-page-zoom-design for doc and UKM request.

Bug: 1232536
Fixed: 1402526
Change-Id: I431d0a05efc1f841650340503f6a3c274eb75307
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4094081
Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Reviewed-by: Mark Schillaci <mschillaci@google.com>
Commit-Queue: Amanda Lin Dietz <aldietz@google.com>
Cr-Commit-Position: refs/heads/main@{#1085286}

components/browser_ui/accessibility/DEPS

@@ -3,5 +3,6 @@ include_rules = [
   "+components/user_prefs",
   "+content/public/android/java",
   "+content/public/browser",
+  "+services/metrics/public/cpp",
   "+ui/android",
 ]

components/browser_ui/accessibility/android/BUILD.gn

@@ -5,20 +5,26 @@
 import("//build/config/android/rules.gni")
 
 generate_jni("accessibility_jni_headers") {
-  sources = [ "java/src/org/chromium/components/browser_ui/accessibility/FontSizePrefs.java" ]
+  sources = [
+    "java/src/org/chromium/components/browser_ui/accessibility/FontSizePrefs.java",
+    "java/src/org/chromium/components/browser_ui/accessibility/PageZoomMetrics.java",
+  ]
 }
 
 source_set("android") {
   sources = [
     "font_size_prefs_android.cc",
     "font_size_prefs_android.h",
+    "page_zoom_metrics.cc",
+    "page_zoom_metrics.h",
   ]
   deps = [
     ":accessibility_jni_headers",
     "//base",
     "//components/prefs",
     "//components/user_prefs",
     "//content/public/browser",
+    "//services/metrics/public/cpp:ukm_builders",
   ]
 }
 
@@ -34,6 +40,7 @@ android_library("java") {
     "java/src/org/chromium/components/browser_ui/accessibility/FontSizePrefs.java",
     "java/src/org/chromium/components/browser_ui/accessibility/PageZoomCoordinator.java",
     "java/src/org/chromium/components/browser_ui/accessibility/PageZoomMediator.java",
+    "java/src/org/chromium/components/browser_ui/accessibility/PageZoomMetrics.java",
     "java/src/org/chromium/components/browser_ui/accessibility/PageZoomPreference.java",
     "java/src/org/chromium/components/browser_ui/accessibility/PageZoomProperties.java",
     "java/src/org/chromium/components/browser_ui/accessibility/PageZoomUma.java",

components/browser_ui/accessibility/android/java/src/org/chromium/components/browser_ui/accessibility/PageZoomCoordinator.java

@@ -131,6 +131,7 @@ public void hide() {
             // Ensure that the user has set a zoom value during this session.
             double zoomValue = mMediator.latestZoomValue();
             if (zoomValue != 0.0) {
+                mMediator.logZoomLevelUKM(zoomValue);
                 PageZoomUma.logAppMenuSliderZoomLevelChangedHistogram();
                 PageZoomUma.logAppMenuSliderZoomLevelValueHistogram(zoomValue);
             }

components/browser_ui/accessibility/android/java/src/org/chromium/components/browser_ui/accessibility/PageZoomMediator.java

@@ -100,6 +100,13 @@ protected double latestZoomValue() {
         return mLatestZoomValue;
     }
 
+    /**
+     * Log UKM for the user changing the zoom level on the page from the slider.
+     */
+    protected void logZoomLevelUKM(double value) {
+        PageZoomMetrics.logZoomLevelUKM(mWebContents, value);
+    }
+
     @VisibleForTesting(otherwise = VisibleForTesting.PRIVATE)
     void handleDecreaseClicked(Void unused) {
         // When decreasing zoom, "snap" to the greatest preset value that is less than the current.

components/browser_ui/accessibility/android/java/src/org/chromium/components/browser_ui/accessibility/PageZoomMetrics.java

@@ -0,0 +1,32 @@
+// Copyright 2022 The Chromium Authors
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.components.browser_ui.accessibility;
+
+import androidx.annotation.NonNull;
+
+import org.chromium.base.annotations.JNINamespace;
+import org.chromium.base.annotations.NativeMethods;
+import org.chromium.content_public.browser.WebContents;
+
+/**
+ * Centralizes metrics data collection for Page Zoom.
+ */
+@JNINamespace("browser_ui")
+public class PageZoomMetrics {
+    /**
+     * Log new zoom level UKM for the given web contents.
+     * Recorded on slider dismissal if the user chose a new value.
+     * @param webContents   WebContents for which to log value
+     * @param newZoomLevel  double - new zoom level
+     */
+    public static void logZoomLevelUKM(@NonNull WebContents webContents, double newZoomLevel) {
+        PageZoomMetricsJni.get().logZoomLevelUKM(webContents, newZoomLevel);
+    }
+
+    @NativeMethods
+    public interface Natives {
+        void logZoomLevelUKM(WebContents webContents, double value);
+    }
+}

components/browser_ui/accessibility/android/page_zoom_metrics.cc

@@ -0,0 +1,35 @@
+// Copyright 2022 The Chromium Authors
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "components/browser_ui/accessibility/android/page_zoom_metrics.h"
+
+#include "base/android/scoped_java_ref.h"
+#include "components/browser_ui/accessibility/android/accessibility_jni_headers/PageZoomMetrics_jni.h"
+#include "content/public/browser/web_contents.h"
+#include "services/metrics/public/cpp/ukm_builders.h"
+#include "services/metrics/public/cpp/ukm_recorder.h"
+#include "services/metrics/public/cpp/ukm_source_id.h"
+
+namespace browser_ui {
+
+using base::android::JavaParamRef;
+using base::android::JavaRef;
+
+void JNI_PageZoomMetrics_LogZoomLevelUKM(
+    JNIEnv* env,
+    const base::android::JavaParamRef<jobject>& j_web_contents,
+    jdouble newZoomLevel) {
+  content::WebContents* web_contents =
+      content::WebContents::FromJavaWebContents(j_web_contents);
+  DCHECK(web_contents);
+
+  ukm::SourceId ukm_source_id =
+      web_contents->GetPrimaryMainFrame()->GetPageUkmSourceId();
+
+  ukm::builders::Accessibility_PageZoom(ukm_source_id)
+      .SetSliderZoomValue((int)round(100 * newZoomLevel))
+      .Record(ukm::UkmRecorder::Get());
+}
+
+}  // namespace browser_ui

components/browser_ui/accessibility/android/page_zoom_metrics.h

@@ -0,0 +1,28 @@
+// Copyright 2022 The Chromium Authors
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef COMPONENTS_BROWSER_UI_ACCESSIBILITY_ANDROID_PAGE_ZOOM_METRICS_H_
+#define COMPONENTS_BROWSER_UI_ACCESSIBILITY_ANDROID_PAGE_ZOOM_METRICS_H_
+
+namespace content {
+class WebContents;
+}
+
+namespace browser_ui {
+
+/*
+ * Native component to log metrics for Page Zoom.
+ */
+class PageZoomMetrics {
+ public:
+  PageZoomMetrics();
+  ~PageZoomMetrics();
+
+  // Logs UKM with the current zoom level for the specified WebContents.
+  void LogZoomLevelUKM(content::WebContents* web_contents, double newZoomLevel);
+};
+
+}  // namespace browser_ui
+
+#endif  // COMPONENTS_BROWSER_UI_ACCESSIBILITY_ANDROID_PAGE_ZOOM_METRICS_H_

tools/metrics/ukm/ukm.xml

@@ -149,6 +149,31 @@ be describing additional metrics about the same event.
   </metric>
 </event>
 
+<event name="Accessibility.PageZoom">
+  <owner>aldietz@google.com</owner>
+  <owner>mschillaci@google.com</owner>
+  <owner>chrome-a11y-core@google.com</owner>
+  <summary>
+    Tracks usage of Page Zoom on Chrome for Android. Recorded each time the
+    slider is dismissed if the user changed the zoom level on this page before
+    dismissal.
+  </summary>
+  <metric name="SliderZoomValue">
+    <summary>
+      For users who changed the individual zoom level on this page, tracks what
+      zoom level has been set on the page at slider dismissal. There may be
+      multiple instances where the slider is opened on the same page, so there
+      may be multiple values logged per page. The value will be an integer
+      between 25 and 500, inclusive.
+    </summary>
+    <aggregation>
+      <history>
+        <statistics/>
+      </history>
+    </aggregation>
+  </metric>
+</event>
+
 <event name="Accessibility.Renderer">
   <owner>aleventhal@chromium.org</owner>
   <owner>nektar@chromium.org</owner>