Splits SmoothGestureController from RenderWidgetHostImpl

tools/telemetry/telemetry/page/actions/scroll.js

 // 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.
 
 // This file provides the ScrollAction object, which scrolls a page
 // from top to bottom:
 //   1. var action = new __ScrollAction(callback)
 //   2. action.start(element_to_scroll)
 'use strict';
 
@@ skipping 55 matching lines @@
     }
     return rect;
   };
 
   SmoothScrollDownGesture.prototype.start = function(distance, callback) {
     this.callback_ = callback;
     if (window.chrome &&
         chrome.gpuBenchmarking &&
         chrome.gpuBenchmarking.smoothScrollBy) {
       var rect = getBoundingVisibleRect(this.element_);
-      chrome.gpuBenchmarking.smoothScrollBy(distance, function() {
-        callback();
-      }, rect.left + rect.width / 2, rect.top + rect.height / 2);
+      var scrolled = chrome.gpuBenchmarking.smoothScrollBy(
+          distance, function() {
+              callback();
+          },
+          rect.left + rect.width / 2, rect.top + rect.height / 2);
+      if (!scrolled)
+        console.log('Unable to start smooth scrolling');
       return;
     }
 
     var SCROLL_DELTA = 100;
     this.element_.scrollTop += SCROLL_DELTA;
     requestAnimationFrame(callback);
   };
 
   // This class scrolls a page from the top to the bottom once.
   //
@@ skipping 63 matching lines @@
     this.endMeasuringHook();
 
     // We're done.
     if (this.callback_)
       this.callback_();
   };
 
   window.__ScrollAction = ScrollAction;
   window.__ScrollAction_GetBoundingVisibleRect = getBoundingVisibleRect;
 })();