Add browsertests for VibrationManager java impl on android.

device/vibration/android/java/src/org/chromium/device/vibration/VibrationManagerImpl.java

 // Copyright 2015 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.device.vibration;
 
 import android.content.Context;
 import android.content.pm.PackageManager;
 import android.media.AudioManager;
 import android.os.Vibrator;
 import android.util.Log;
 
+import org.chromium.base.VisibleForTesting;
 import org.chromium.mojo.system.MojoException;
 import org.chromium.mojom.device.VibrationManager;
 
 /**
  * Android implementation of the vibration manager service defined in
  * device/vibration/vibration_manager.mojom.
  */
 public class VibrationManagerImpl implements VibrationManager {
     private static final String TAG = "VibrationManagerImpl";
 
     private static final long MINIMUM_VIBRATION_DURATION_MS = 1; // 1 millisecond
     private static final long MAXIMUM_VIBRATION_DURATION_MS = 10000; // 10 seconds
 
     private final AudioManager mAudioManager;
-    private final Vibrator mVibrator;
     private final boolean mHasVibratePermission;
 
+    private static AndroidVibratorWrapper sVibratorWrapper;
+
+    /**
+     * Android Vibrator wrapper class provided to test code to extend.
+     */
+    @VisibleForTesting
+    public static class AndroidVibratorWrapper {

[timvolodine, 2015/09/11 16:40:15]

normally we try to minimize test-related code in production, so it's best to
define something like this in the ..Test file.

[leonhsl(Using Gerrit), 2015/09/22 09:56:19]

As bellowing discussion.

+        private final Vibrator mAndroidVibrator;
+
+        protected AndroidVibratorWrapper(Vibrator vibrator) {
+            mAndroidVibrator = vibrator;
+        }
+
+        public void vibrate(long milliseconds) {
+            mAndroidVibrator.vibrate(milliseconds);
+        }
+
+        public void cancel() {
+            mAndroidVibrator.cancel();
+        }
+    }
+
+    // Test code can use this function to inject other wrapper for testing.
+    public static void setVibratorWrapperForTesting(AndroidVibratorWrapper wrapper) {

[timvolodine, 2015/09/11 16:40:15]

I think ideally the way to test this would be to inject a fake vibration manager
service into java registry during the test. The fake service would derive from
this class and set mVibrator android service to a mock implementation.

[leonhsl(Using Gerrit), 2015/09/22 09:56:19]

ContentBrowserClient provides OverrideRenderProcessMojoServices() which allows
to override to inject new C++ mojo service into *ServiceRegistry* of
RenderProcessHost. 
But as for java mojo services, they're added into the *ServiceRegistry* via JNI
function registerProcessHostServices() in ServiceRegistrar.java. Java test code
based on ContentShellTestBase class have no entry to override the registering
process.
Although I investigated around lots, did not find a good point to do this... If
possible would you please help to give some hints~~

+        sVibratorWrapper = wrapper;
+    }
+
     public VibrationManagerImpl(Context context) {
         mAudioManager = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
-        mVibrator = (Vibrator) context.getSystemService(Context.VIBRATOR_SERVICE);
+        if (sVibratorWrapper == null) {
+            sVibratorWrapper = new AndroidVibratorWrapper(
+                    (Vibrator) context.getSystemService(Context.VIBRATOR_SERVICE));
+        }
         mHasVibratePermission =
                 context.checkCallingOrSelfPermission(android.Manifest.permission.VIBRATE)
                 == PackageManager.PERMISSION_GRANTED;
         if (!mHasVibratePermission) {
             Log.w(TAG, "Failed to use vibrate API, requires VIBRATE permission.");
         }
     }
 
     @Override
     public void close() {}
 
     @Override
     public void onConnectionError(MojoException e) {}
 
     @Override
     public void vibrate(long milliseconds) {
         // Though the Blink implementation already sanitizes vibration times, don't
         // trust any values passed from the client.
         long sanitizedMilliseconds = Math.max(MINIMUM_VIBRATION_DURATION_MS,
                 Math.min(milliseconds, MAXIMUM_VIBRATION_DURATION_MS));
 
         if (mAudioManager.getRingerMode() != AudioManager.RINGER_MODE_SILENT
                 && mHasVibratePermission) {
-            mVibrator.vibrate(sanitizedMilliseconds);
+            sVibratorWrapper.vibrate(sanitizedMilliseconds);
         }
     }
 
     @Override
     public void cancel() {
-        if (mHasVibratePermission) mVibrator.cancel();
+        if (mHasVibratePermission) sVibratorWrapper.cancel();
     }
 }