Implement mix-blend-mode in GL renderer using shaders.

cc/output/program_binding.h

 // Copyright 2011 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_PROGRAM_BINDING_H_
 #define CC_OUTPUT_PROGRAM_BINDING_H_
 
 #include <string>
 
 #include "base/logging.h"
@@ skipping 40 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(ProgramBindingBase);
 };
 
 template <class VertexShader, class FragmentShader>
 class ProgramBinding : public ProgramBindingBase {
  public:
   ProgramBinding() {}
 
   void Initialize(ContextProvider* context_provider,
                   TexCoordPrecision precision,
-                  SamplerType sampler) {
+                  SamplerType sampler,
+                  BlendMode blend_mode = BlendModeNormal) {
     DCHECK(context_provider);
     DCHECK(!initialized_);
 
     if (context_provider->IsContextLost())
       return;
 
+    fragment_shader_.set_blend_mode(blend_mode);
+
     if (!ProgramBindingBase::Init(
             context_provider->ContextGL(),
             vertex_shader_.GetShaderString(),
             fragment_shader_.GetShaderString(precision, sampler))) {
       DCHECK(context_provider->IsContextLost());
       return;
     }
 
     int base_uniform_index = 0;
     vertex_shader_.Init(context_provider->ContextGL(),
@@ skipping 16 matching lines @@
  private:
   VertexShader vertex_shader_;
   FragmentShader fragment_shader_;
 
   DISALLOW_COPY_AND_ASSIGN(ProgramBinding);
 };
 
 }  // namespace cc
 
 #endif  // CC_OUTPUT_PROGRAM_BINDING_H_