Adaptively throttle texture uploads

cc/TextureUploader.h

 // Copyright 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.
 
 #ifndef TextureUploader_h
 #define TextureUploader_h
 
 #include "LayerTextureUpdater.h"
 
 namespace WebCore {
 
 class TextureUploader {
 public:
     struct Parameters {
         LayerTextureUpdater::Texture* texture;
         IntRect sourceRect;
         IntSize destOffset;
     };
 
     virtual ~TextureUploader() { }
 
     virtual bool isBusy() = 0;
+
+    // Returns our throughput on the GPU process
+    virtual double estimatedPixelsPerSecond() = 0;
     virtual void beginUploads() = 0;
     virtual void endUploads() = 0;
     virtual void uploadTexture(CCResourceProvider*, Parameters) = 0;
 };
 
 }
 
 #endif