Keep screen on when there is an active WebRTC session on Android.

android_webview/java/src/org/chromium/android_webview/AwContentVideoViewDelegate.java

 // Copyright (c) 2012 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.android_webview;
 
 import android.content.Context;
 import android.content.pm.ActivityInfo;
 import android.view.View;
 import android.webkit.WebChromeClient.CustomViewCallback;
@@ skipping 23 matching lines @@
         };
         mAwContentsClient.onShowCustomView(view, cb);
     }
 
     @Override
     public void onDestroyContentVideoView() {
         mAwContentsClient.onHideCustomView();
     }
 
     @Override
+    public void keepScreenOn(boolean screenOn) {
+    }
+
+    @Override
     public Context getContext() {
         return mContext;
     }
 
     @Override
     public View getVideoLoadingProgressView() {
         return mAwContentsClient.getVideoLoadingProgressView();
     }
 }