Add methods to GPU extensions to precisely determine visual viewport dimensions.

content/renderer/gpu/gpu_benchmarking_extension.h

 // 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.
 
 #ifndef CONTENT_RENDERER_GPU_GPU_BENCHMARKING_EXTENSION_H_
 #define CONTENT_RENDERER_GPU_GPU_BENCHMARKING_EXTENSION_H_
 
 #include "base/macros.h"
 #include "gin/wrappable.h"
 
@@ skipping 30 matching lines @@
   // JavaScript handlers.
   void SetNeedsDisplayOnAllLayers();
   void SetRasterizeOnlyVisibleContent();
   void PrintToSkPicture(v8::Isolate* isolate, const std::string& dirname);
   bool GestureSourceTypeSupported(int gesture_source_type);
   bool SmoothScrollBy(gin::Arguments* args);
   bool SmoothDrag(gin::Arguments* args);
   bool Swipe(gin::Arguments* args);
   bool ScrollBounce(gin::Arguments* args);
   bool PinchBy(gin::Arguments* args);
+  float VisualViewportX();
+  float VisualViewportY();
   float VisualViewportHeight();
   float VisualViewportWidth();
+  float PageScaleFactor();
   bool Tap(gin::Arguments* args);
   void ClearImageCache();
   int RunMicroBenchmark(gin::Arguments* args);
   bool SendMessageToMicroBenchmark(int id, v8::Local<v8::Object> message);
   bool HasGpuChannel();
   bool HasGpuProcess();
 
   DISALLOW_COPY_AND_ASSIGN(GpuBenchmarking);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_GPU_GPU_BENCHMARKING_EXTENSION_H_