DevTools: optimize screencast for slower devices.

third_party/WebKit/Source/devtools/front_end/screencast/ScreencastView.js

Index: third_party/WebKit/Source/devtools/front_end/screencast/ScreencastView.js
diff --git a/third_party/WebKit/Source/devtools/front_end/screencast/ScreencastView.js b/third_party/WebKit/Source/devtools/front_end/screencast/ScreencastView.js
index fc42e9bcfd459ba0e22c482a3f576f269ba703ff..07d10770ed43adf4200d7c8ff769658c4655fa7b 100644
--- a/third_party/WebKit/Source/devtools/front_end/screencast/ScreencastView.js
+++ b/third_party/WebKit/Source/devtools/front_end/screencast/ScreencastView.js
@@ -150,6 +150,8 @@ WebInspector.ScreencastView.prototype = {
      */
     _screencastFrame: function(event)
     {
+        this._target.pageAgent().screencastFrameAck();
+
         var metadata = /** type {PageAgent.ScreencastFrameMetadata} */(event.data.metadata);
         var base64Data = /** type {string} */(event.data.data);
         this._imageElement.src = "data:image/jpg;base64," + base64Data;
@@ -158,9 +160,6 @@ WebInspector.ScreencastView.prototype = {
         this._scrollOffsetX = metadata.scrollOffsetX;
         this._scrollOffsetY = metadata.scrollOffsetY;
 
-        if (event.data.frameNumber)
-            this._target.pageAgent().screencastFrameAck(event.data.frameNumber);
-
         var deviceSizeRatio = metadata.deviceHeight / metadata.deviceWidth;
         var dimensionsCSS = this._viewportDimensions();