gpu: Add ARB_occlusion_query support.

cc/output/gl_renderer.h

 // Copyright 2010 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 CC_OUTPUT_GL_RENDERER_H_
 #define CC_OUTPUT_GL_RENDERER_H_
 
 #include <deque>
 #include <vector>
 
@@ skipping 260 matching lines @@
                                   DrawingFrame* external_frame);
 
   // Setup/flush all pending overdraw feedback to framebuffer.
   void SetupOverdrawFeedback();
   void FlushOverdrawFeedback(const DrawingFrame* frame,
                              const gfx::Rect& output_rect);
   // Process overdraw feedback from query.
   using OverdrawFeedbackCallback = base::Callback<void(unsigned, int)>;
   void ProcessOverdrawFeedback(std::vector<int>* overdraw,
                                size_t num_expected_results,
+                               int max_result,
                                unsigned query,
                                int multiplier);
 
   using OverlayResourceLock =
       std::unique_ptr<ResourceProvider::ScopedReadLockGL>;
   using OverlayResourceLockList = std::vector<OverlayResourceLock>;
 
   // Resources that have been sent to the GPU process, but not yet swapped.
   OverlayResourceLockList pending_overlay_resources_;
 
@@ skipping 66 matching lines @@
   // The method FlippedFramebuffer determines whether the framebuffer associated
   // with a DrawingFrame is flipped. It makes the assumption that the
   // DrawingFrame is being used as part of a render pass. If a DrawingFrame is
   // not being used as part of a render pass, setting it here forces
   // FlippedFramebuffer to return |true|.
   bool force_drawing_frame_framebuffer_unflipped_ = false;
 
   BoundGeometry bound_geometry_;
   ColorLUTCache color_lut_cache_;
 
+  bool use_occlusion_query_;
   unsigned offscreen_stencil_renderbuffer_id_ = 0;
   gfx::Size offscreen_stencil_renderbuffer_size_;
 
   base::WeakPtrFactory<GLRenderer> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(GLRenderer);
 };
 
 }  // namespace cc
 
 #endif  // CC_OUTPUT_GL_RENDERER_H_