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

cc/output/shader.h

Index: cc/output/shader.h
diff --git a/cc/output/shader.h b/cc/output/shader.h
index 3039c80ef2c790f3506babb6b4f714fd8571280b..e759531e8435faf33ffaa11c84952624ddb5c622 100644
--- a/cc/output/shader.h
+++ b/cc/output/shader.h
@@ -9,6 +9,7 @@
 
 #include "base/basictypes.h"
 #include "cc/base/cc_export.h"
+#include "third_party/skia/include/core/SkXfermode.h"
 
 namespace gfx {
 class Point;
@@ -279,7 +280,35 @@ class VertexShaderVideoTransform {
   DISALLOW_COPY_AND_ASSIGN(VertexShaderVideoTransform);
 };
 
-class FragmentTexAlphaBinding {
+class FragmentTexBlendMode {
+ public:
+  int backdrop_location() const { return backdrop_location_; }
+  int backdrop_rect_location() const { return backdrop_rect_location_; }
+
+  SkXfermode::Mode blend_mode() const { return blend_mode_; }
+  bool is_default_blend_mode() const {
+    return blend_mode_ == SkXfermode::kSrcOver_Mode;
+  }
+  inline static bool is_blend_mode_supported(SkXfermode::Mode blend_mode);
+
+  void SetBlendMode(SkXfermode::Mode blend_mode);
+
+ protected:
+  FragmentTexBlendMode();
+
+  std::string SetBlendModeFunctions(std::string shader_string) const;
+
+  int backdrop_location_;
+  int backdrop_rect_location_;
+
+ private:
+  SkXfermode::Mode blend_mode_;
+
+  std::string GetHelperFunctions() const;
+  std::string GetMainBlendingCode() const;
+};
+
+class FragmentTexAlphaBinding : public FragmentTexBlendMode {
  public:
   FragmentTexAlphaBinding();
 
@@ -297,7 +326,7 @@ class FragmentTexAlphaBinding {
   DISALLOW_COPY_AND_ASSIGN(FragmentTexAlphaBinding);
 };
 
-class FragmentTexColorMatrixAlphaBinding {
+class FragmentTexColorMatrixAlphaBinding : public FragmentTexBlendMode {
  public:
     FragmentTexColorMatrixAlphaBinding();
 
@@ -317,7 +346,7 @@ class FragmentTexColorMatrixAlphaBinding {
     int color_offset_location_;
 };
 
-class FragmentTexOpaqueBinding {
+class FragmentTexOpaqueBinding : public FragmentTexBlendMode {
  public:
   FragmentTexOpaqueBinding();
 
@@ -335,7 +364,7 @@ class FragmentTexOpaqueBinding {
   DISALLOW_COPY_AND_ASSIGN(FragmentTexOpaqueBinding);
 };
 
-class FragmentTexBackgroundBinding {
+class FragmentTexBackgroundBinding : public FragmentTexBlendMode {
  public:
   FragmentTexBackgroundBinding();
 
@@ -417,7 +446,7 @@ class FragmentShaderRGBATexSwizzleOpaque : public FragmentTexOpaqueBinding {
       TexCoordPrecision precision, SamplerType sampler) const;
 };
 
-class FragmentShaderRGBATexAlphaAA {
+class FragmentShaderRGBATexAlphaAA : public FragmentTexBlendMode {
  public:
   FragmentShaderRGBATexAlphaAA();
 
@@ -437,7 +466,7 @@ class FragmentShaderRGBATexAlphaAA {
   DISALLOW_COPY_AND_ASSIGN(FragmentShaderRGBATexAlphaAA);
 };
 
-class FragmentTexClampAlphaAABinding {
+class FragmentTexClampAlphaAABinding : public FragmentTexBlendMode {
  public:
   FragmentTexClampAlphaAABinding();
 
@@ -473,7 +502,7 @@ class FragmentShaderRGBATexClampSwizzleAlphaAA
       TexCoordPrecision precision, SamplerType sampler) const;
 };
 
-class FragmentShaderRGBATexAlphaMask {
+class FragmentShaderRGBATexAlphaMask : public FragmentTexBlendMode {
  public:
   FragmentShaderRGBATexAlphaMask();
   std::string GetShaderString(
@@ -502,7 +531,7 @@ class FragmentShaderRGBATexAlphaMask {
   DISALLOW_COPY_AND_ASSIGN(FragmentShaderRGBATexAlphaMask);
 };
 
-class FragmentShaderRGBATexAlphaMaskAA {
+class FragmentShaderRGBATexAlphaMaskAA : public FragmentTexBlendMode {
  public:
   FragmentShaderRGBATexAlphaMaskAA();
   std::string GetShaderString(
@@ -531,7 +560,8 @@ class FragmentShaderRGBATexAlphaMaskAA {
   DISALLOW_COPY_AND_ASSIGN(FragmentShaderRGBATexAlphaMaskAA);
 };
 
-class FragmentShaderRGBATexAlphaMaskColorMatrixAA {
+class FragmentShaderRGBATexAlphaMaskColorMatrixAA
+    : public FragmentTexBlendMode {
  public:
   FragmentShaderRGBATexAlphaMaskColorMatrixAA();
   std::string GetShaderString(
@@ -562,7 +592,7 @@ class FragmentShaderRGBATexAlphaMaskColorMatrixAA {
   int color_offset_location_;
 };
 
-class FragmentShaderRGBATexAlphaColorMatrixAA {
+class FragmentShaderRGBATexAlphaColorMatrixAA : public FragmentTexBlendMode {
  public:
   FragmentShaderRGBATexAlphaColorMatrixAA();
   std::string GetShaderString(
@@ -583,7 +613,7 @@ class FragmentShaderRGBATexAlphaColorMatrixAA {
   int color_offset_location_;
 };
 
-class FragmentShaderRGBATexAlphaMaskColorMatrix {
+class FragmentShaderRGBATexAlphaMaskColorMatrix : public FragmentTexBlendMode {
  public:
   FragmentShaderRGBATexAlphaMaskColorMatrix();
   std::string GetShaderString(
@@ -614,7 +644,7 @@ class FragmentShaderRGBATexAlphaMaskColorMatrix {
   int color_offset_location_;
 };
 
-class FragmentShaderYUVVideo {
+class FragmentShaderYUVVideo : public FragmentTexBlendMode {
  public:
   FragmentShaderYUVVideo();
   std::string GetShaderString(
@@ -641,8 +671,7 @@ class FragmentShaderYUVVideo {
   DISALLOW_COPY_AND_ASSIGN(FragmentShaderYUVVideo);
 };
 
-
-class FragmentShaderYUVAVideo {
+class FragmentShaderYUVAVideo : public FragmentTexBlendMode {
  public:
   FragmentShaderYUVAVideo();
   std::string GetShaderString(
@@ -672,7 +701,7 @@ class FragmentShaderYUVAVideo {
   DISALLOW_COPY_AND_ASSIGN(FragmentShaderYUVAVideo);
 };
 
-class FragmentShaderColor {
+class FragmentShaderColor : public FragmentTexBlendMode {
  public:
   FragmentShaderColor();
   std::string GetShaderString(
@@ -689,7 +718,7 @@ class FragmentShaderColor {
   DISALLOW_COPY_AND_ASSIGN(FragmentShaderColor);
 };
 
-class FragmentShaderColorAA {
+class FragmentShaderColorAA : public FragmentTexBlendMode {
  public:
   FragmentShaderColorAA();
   std::string GetShaderString(
@@ -706,7 +735,7 @@ class FragmentShaderColorAA {
   DISALLOW_COPY_AND_ASSIGN(FragmentShaderColorAA);
 };
 
-class FragmentShaderCheckerboard {
+class FragmentShaderCheckerboard : public FragmentTexBlendMode {
  public:
   FragmentShaderCheckerboard();
   std::string GetShaderString(