DevTools: Add snapshot command log on the frontend.

Source/core/inspector/InspectorLayerTreeAgent.cpp

 /*
  * Copyright (C) 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 364 matching lines @@
     outTimings = TypeBuilder::Array<TypeBuilder::Array<double> >::create();
     for (size_t i = 0; i < timings->size(); ++i) {
         const Vector<double>& row = (*timings)[i];
         RefPtr<TypeBuilder::Array<double> > outRow = TypeBuilder::Array<double>::create();
         for (size_t j = 1; j < row.size(); ++j)
             outRow->addItem(row[j] - row[j - 1]);
         outTimings->addItem(outRow.release());
     }
 }
 
-void InspectorLayerTreeAgent::snapshotCommandLog(ErrorString* errorString, const String& snapshotId, RefPtr<TypeBuilder::Array<JSONObject> >& commandLog)
+void InspectorLayerTreeAgent::snapshotCommandLog(ErrorString* errorString, const String& snapshotId, const int* fromStep, const int* toStep, RefPtr<TypeBuilder::Array<JSONObject> >& commandLog)
 {
     const GraphicsContextSnapshot* snapshot = snapshotById(errorString, snapshotId);
     if (!snapshot)
         return;
-    commandLog = TypeBuilder::Array<JSONObject>::runtimeCast(snapshot->snapshotCommandLog());
+    commandLog = TypeBuilder::Array<JSONObject>::runtimeCast(snapshot->snapshotCommandLog(fromStep ? *fromStep : 0, toStep ? *toStep : 0));
 }
 
 void InspectorLayerTreeAgent::willAddPageOverlay(const GraphicsLayer* layer)
 {
     m_pageOverlayLayerIds.append(layer->platformLayer()->id());
 }
 
 void InspectorLayerTreeAgent::didRemovePageOverlay(const GraphicsLayer* layer)
 {
     size_t index = m_pageOverlayLayerIds.find(layer->platformLayer()->id());
     if (index == WTF::kNotFound)
         return;
     m_pageOverlayLayerIds.remove(index);
 }
 
 
 } // namespace WebCore