[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/1330827
Reviewed-by: Yaron Friedman <[email protected]>
Reviewed-by: Dominic Mazzoni <[email protected]>
Reviewed-by: Ilya Sherman <[email protected]>
Commit-Queue: Stephen McGruer <[email protected]>
Cr-Commit-Position: refs/heads/master@{#608052}
diff --git a/content/browser/accessibility/browser_accessibility_state_impl.cc b/content/browser/accessibility/browser_accessibility_state_impl.cc
index 2c185d0ad..24aaa70 100644
--- a/content/browser/accessibility/browser_accessibility_state_impl.cc
+++ b/content/browser/accessibility/browser_accessibility_state_impl.cc
@@ -71,7 +71,7 @@
   // 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 @@
       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 @@
   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() {