[cc] Add SkBlendMode::kDstIn support to cc::Layer

cc/output/shader.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_SHADER_H_
 #define CC_OUTPUT_SHADER_H_
 
 #include <string>
 
 #include "base/logging.h"
@@ skipping 69 matching lines @@
 enum SamplerType {
   SAMPLER_TYPE_NA = 0,
   SAMPLER_TYPE_2D = 1,
   SAMPLER_TYPE_2D_RECT = 2,
   SAMPLER_TYPE_EXTERNAL_OES = 3,
 };
 
 enum BlendMode {
   BLEND_MODE_NONE,
   BLEND_MODE_NORMAL,
+  BLEND_MODE_DESTINATION_IN,
   BLEND_MODE_SCREEN,
   BLEND_MODE_OVERLAY,
   BLEND_MODE_DARKEN,
   BLEND_MODE_LIGHTEN,
   BLEND_MODE_COLOR_DODGE,
   BLEND_MODE_COLOR_BURN,
   BLEND_MODE_HARD_LIGHT,
   BLEND_MODE_SOFT_LIGHT,
   BLEND_MODE_DIFFERENCE,
   BLEND_MODE_EXCLUSION,
@@ skipping 201 matching lines @@
   int lut_texture_location_ = -1;
   int lut_size_location_ = -1;
   int resource_multiplier_location_ = -1;
   int resource_offset_location_ = -1;
 
  private:
   friend class Program;
 
   std::string GetHelperFunctions() const;
   std::string GetBlendFunction() const;
+  std::string GetBlendFunctionBodyForAlpha() const;
   std::string GetBlendFunctionBodyForRGB() const;
 
   DISALLOW_COPY_AND_ASSIGN(FragmentShader);
 };
 
 }  // namespace cc
 
 #endif  // CC_OUTPUT_SHADER_H_