[Accessibility] Add histograms for Android reduce-motion API

This histogram will be used to guide the implementation of the CSS
prefers-reduced-motion media feature. The primary goal is to compare
usage levels across platforms.

Bug: 722548
Change-Id: I9162d4e9df2e04afa0c8716266c2f0dc2c57b2ac
Reviewed-on: https://chromium-review.googlesource.com/c/1330827Reviewed-by: Yaron Friedman <yfriedman@chromium.org>
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Commit-Queue: Stephen McGruer <smcgruer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#608052}

content/browser/BUILD.gn

@@ -2177,6 +2177,7 @@ jumbo_source_set("browser") {
       "accessibility/browser_accessibility_android.h",
       "accessibility/browser_accessibility_manager_android.cc",
       "accessibility/browser_accessibility_manager_android.h",
+      "accessibility/browser_accessibility_state_impl_android.cc",
       "accessibility/captioning_controller.cc",
       "accessibility/captioning_controller.h",
       "accessibility/web_contents_accessibility_android.cc",

content/browser/accessibility/browser_accessibility_state_impl.cc

@@ -71,7 +71,7 @@ BrowserAccessibilityStateImpl::BrowserAccessibilityStateImpl()
   // Let each platform do its own initialization.
   PlatformInitialize();
 
-#if defined(OS_WIN)
+#if defined(OS_WIN) || defined(OS_ANDROID)
   // The delay is necessary because assistive technology sometimes isn't
   // detected until after the user interacts in some way, so a reasonable delay
   // gives us better numbers.
@@ -80,8 +80,8 @@ BrowserAccessibilityStateImpl::BrowserAccessibilityStateImpl()
       base::Bind(&BrowserAccessibilityStateImpl::UpdateHistograms, this),
       base::TimeDelta::FromSeconds(ACCESSIBILITY_HISTOGRAM_DELAY_SECS));
 #else
-  // On all other platforms, UpdateHistograms should be called on the UI
-  // thread because it needs to be able to access PrefService.
+  // On MacOS, UpdateHistograms should be called on the UI thread because it
+  // needs to be able to access PrefService.
   base::PostDelayedTaskWithTraits(
       FROM_HERE, {BrowserThread::UI},
       base::BindOnce(&BrowserAccessibilityStateImpl::UpdateHistograms, this),
@@ -170,7 +170,7 @@ ui::AXMode BrowserAccessibilityStateImpl::GetAccessibilityMode() const {
   return accessibility_mode_;
 }
 
-#if !defined(OS_WIN) && !defined(OS_MACOSX)
+#if !defined(OS_ANDROID) && !defined(OS_WIN) && !defined(OS_MACOSX)
 void BrowserAccessibilityStateImpl::PlatformInitialize() {}
 
 void BrowserAccessibilityStateImpl::UpdatePlatformSpecificHistograms() {

content/browser/accessibility/browser_accessibility_state_impl_android.cc

+// 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.
+
+#include "content/browser/accessibility/browser_accessibility_state_impl.h"
+
+#include "base/android/jni_android.h"
+#include "content/public/browser/browser_thread.h"
+#include "jni/BrowserAccessibilityState_jni.h"
+
+using base::android::AttachCurrentThread;
+
+namespace content {
+
+void BrowserAccessibilityStateImpl::PlatformInitialize() {}
+
+void BrowserAccessibilityStateImpl::UpdatePlatformSpecificHistograms() {
+  // NOTE: this method is run from the file thread to reduce jank, since
+  // there's no guarantee these system calls will return quickly. Be careful
+  // not to add any code that isn't safe to run from a non-main thread!
+  DCHECK(!BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  JNIEnv* env = AttachCurrentThread();
+  Java_BrowserAccessibilityState_recordAccessibilityHistograms(env);
+}
+
+}  // namespace content

content/public/android/BUILD.gn

@@ -152,6 +152,7 @@ android_library("content_java") {
     "java/src/org/chromium/content/browser/accessibility/LollipopWebContentsAccessibility.java",
     "java/src/org/chromium/content/browser/accessibility/OWebContentsAccessibility.java",
     "java/src/org/chromium/content/browser/accessibility/WebContentsAccessibilityImpl.java",
+    "java/src/org/chromium/content/browser/accessibility/BrowserAccessibilityState.java",
     "java/src/org/chromium/content/browser/accessibility/captioning/CaptioningBridgeFactory.java",
     "java/src/org/chromium/content/browser/accessibility/captioning/CaptioningChangeDelegate.java",
     "java/src/org/chromium/content/browser/accessibility/captioning/CaptioningController.java",
@@ -382,6 +383,7 @@ generate_jni("content_jni_headers") {
     "java/src/org/chromium/content/browser/SpeechRecognitionImpl.java",
     "java/src/org/chromium/content/browser/SyntheticGestureTarget.java",
     "java/src/org/chromium/content/browser/TracingControllerAndroidImpl.java",
+    "java/src/org/chromium/content/browser/accessibility/BrowserAccessibilityState.java",
     "java/src/org/chromium/content/browser/accessibility/WebContentsAccessibilityImpl.java",
     "java/src/org/chromium/content/browser/accessibility/captioning/CaptioningController.java",
     "java/src/org/chromium/content/browser/androidoverlay/AndroidOverlayProviderImpl.java",

content/public/android/java/src/org/chromium/content/browser/accessibility/BrowserAccessibilityState.java

+// 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.
+
+package org.chromium.content.browser.accessibility;
+
+import android.annotation.TargetApi;
+import android.os.Build;
+import android.provider.Settings;
+
+import org.chromium.base.ContextUtils;
+import org.chromium.base.annotations.CalledByNative;
+import org.chromium.base.annotations.JNINamespace;
+import org.chromium.base.metrics.RecordHistogram;
+
+/**
+ * Provides utility methods relating to measuring accessibility state on the current platform (i.e.
+ * Android in this case). See content::BrowserAccessibilityStateImpl.
+ */
+@JNINamespace("content")
+public class BrowserAccessibilityState {
+    @CalledByNative
+    @TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR1)
+    private static void recordAccessibilityHistograms() {
+        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN_MR1) return;
+
+        float durationScale =
+                Settings.Global.getFloat(ContextUtils.getApplicationContext().getContentResolver(),
+                        Settings.Global.ANIMATOR_DURATION_SCALE, 0);
+        RecordHistogram.recordBooleanHistogram(
+                "Accessibility.Android.AnimationsEnabled", durationScale != 0.0);
+    }
+}

tools/metrics/histograms/histograms.xml

@@ -25,6 +25,18 @@ uploading your change for review.
 
 <histograms>
 
+<histogram name="Accessibility.Android.AnimationsEnabled" enum="BooleanEnabled"
+    expires_after="2019-11-02">
+  <owner>dmazzoni@chromium.org</owner>
+  <owner>smcgruer@chromium.org</owner>
+  <summary>
+    Tracks whether animations are enabled on Android (e.g. if the animator
+    duration scale is non-zero.) The purpose is to inform the design of the
+    prefers-reduced-motion media feature; see http://crbug.com/722548. This is
+    checked once, 45 seconds after startup.
+  </summary>
+</histogram>
+
 <histogram name="Accessibility.Android.TabSwitcherPreferenceEnabled"
     enum="BooleanEnabled">
   <owner>twellington@chromium.org</owner>
@@ -339,7 +351,8 @@ uploading your change for review.
   </summary>
 </histogram>
 
-<histogram name="Accessibility.Mac.ReduceMotion" enum="BooleanEnabled">
+<histogram name="Accessibility.Mac.ReduceMotion" enum="BooleanEnabled"
+    expires_after="2019-11-02">
   <owner>dmazzoni@chromium.org</owner>
   <owner>smcgruer@chromium.org</owner>
   <summary>