Add browsertests for VibrationManager java impl on android.

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

Index: device/vibration/android/java/src/org/chromium/device/vibration/VibrationManagerImpl.java
diff --git a/device/vibration/android/java/src/org/chromium/device/vibration/VibrationManagerImpl.java b/device/vibration/android/java/src/org/chromium/device/vibration/VibrationManagerImpl.java
index dd8d2755c8a5df286dc21bf4d9dd33518aaf8c69..f0ddbc98eb79d04233e31f7e53688964638018ef 100644
--- a/device/vibration/android/java/src/org/chromium/device/vibration/VibrationManagerImpl.java
+++ b/device/vibration/android/java/src/org/chromium/device/vibration/VibrationManagerImpl.java
@@ -10,6 +10,7 @@ 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;
 
@@ -24,12 +25,41 @@ public class VibrationManagerImpl implements VibrationManager {
     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;
@@ -53,12 +83,12 @@ public class VibrationManagerImpl implements VibrationManager {
 
         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();
     }
 }