Implement mix-blend-mode=screen using glBlendFunc.

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 "base/cancelable_callback.h"
 #include "cc/base/cc_export.h"
 #include "cc/base/scoped_ptr_deque.h"
@@ skipping 125 matching lines @@
  private:
   friend class GLRendererShaderPixelTest;
   friend class GLRendererShaderTest;
 
   static void ToGLMatrix(float* gl_matrix, const gfx::Transform& transform);
 
   void DrawCheckerboardQuad(const DrawingFrame* frame,
                             const CheckerboardDrawQuad* quad);
   void DrawDebugBorderQuad(const DrawingFrame* frame,
                            const DebugBorderDrawQuad* quad);
+  static bool ShouldApplyBackgroundFilters(DrawingFrame* frame,
+                                           const RenderPassDrawQuad* quad);
+  static bool ShouldApplyBlendModeUsingBlendFunc(const DrawQuad* quad);
+  void ApplyBlendModeUsingBlendFunc(const DrawQuad* quad);
+  void RestoreBlendFuncToDefault(const DrawQuad* quad);
   scoped_ptr<ScopedResource> GetBackgroundWithFilters(
       DrawingFrame* frame,
       const RenderPassDrawQuad* quad,
       const gfx::Transform& contents_device_transform,
       const gfx::Transform& contents_device_transformInverse,
       bool* background_changed);
   void DrawRenderPassQuad(DrawingFrame* frame, const RenderPassDrawQuad* quad);
   void DrawSolidColorQuad(const DrawingFrame* frame,
                           const SolidColorDrawQuad* quad);
   void DrawStreamVideoQuad(const DrawingFrame* frame,
@@ skipping 277 matching lines @@
 #if DEBUG_GL_CALLS && !defined(NDEBUG)
 #define GLC(context, x)                                                        \
   (x, GLRenderer::DebugGLCall(&* context, #x, __FILE__, __LINE__))
 #else
 #define GLC(context, x) (x)
 #endif
 
 }  // namespace cc
 
 #endif  // CC_OUTPUT_GL_RENDERER_H_