cc: Use highp precision for texture coords if available and needed

cc/output/shader.h

Index: cc/output/shader.h
diff --git a/cc/output/shader.h b/cc/output/shader.h
index 49b2e6629b4337053aa7e0a798ec630e84d9c5d6..24d541756ef01abc0cc42b47bc38a7661f5d4aed 100644
--- a/cc/output/shader.h
+++ b/cc/output/shader.h
@@ -8,12 +8,28 @@
 #include <string>
 #include "third_party/skia/include/core/SkColorPriv.h"
 
+namespace gfx {
+class Point;
+}
+
 namespace WebKit {
 class WebGraphicsContext3D;
 }
 
 namespace cc {
 
+enum TexCoordPrecision {
+  TexCoordPrecisionNA,
+  TexCoordPrecisionMedium,
+  TexCoordPrecisionHigh,
+};
+
+int TexCoordHighpThreshold(WebKit::WebGraphicsContext3D* context);
+
+TexCoordPrecision TexCoordPrecisionRequired(
+    WebKit::WebGraphicsContext3D* context,
+    const gfx::Point& max_coordinate);
+
 class VertexShaderPosTex {
  public:
   VertexShaderPosTex();
@@ -195,45 +211,45 @@ class FragmentTexOpaqueBinding {
 
 class FragmentShaderRGBATexVaryingAlpha : public FragmentTexOpaqueBinding {
  public:
-  std::string GetShaderString() const;
+  std::string GetShaderString(TexCoordPrecision precision) const;
 };
 
 class FragmentShaderRGBATexAlpha : public FragmentTexAlphaBinding {
 public:
-  std::string GetShaderString() const;
+  std::string GetShaderString(TexCoordPrecision precision) const;
 };
 
 class FragmentShaderRGBATexRectVaryingAlpha : public FragmentTexAlphaBinding {
  public:
-  std::string GetShaderString() const;
+  std::string GetShaderString(TexCoordPrecision precision) const;
 };
 
 class FragmentShaderRGBATexOpaque : public FragmentTexOpaqueBinding {
  public:
-  std::string GetShaderString() const;
+  std::string GetShaderString(TexCoordPrecision precision) const;
 };
 
 class FragmentShaderRGBATex : public FragmentTexOpaqueBinding {
  public:
-  std::string GetShaderString() const;
+  std::string GetShaderString(TexCoordPrecision precision) const;
 };
 
 // Swizzles the red and blue component of sampled texel with alpha.
 class FragmentShaderRGBATexSwizzleAlpha : public FragmentTexAlphaBinding {
  public:
-  std::string GetShaderString() const;
+  std::string GetShaderString(TexCoordPrecision precision) const;
 };
 
 // Swizzles the red and blue component of sampled texel without alpha.
 class FragmentShaderRGBATexSwizzleOpaque : public FragmentTexOpaqueBinding {
  public:
-  std::string GetShaderString() const;
+  std::string GetShaderString(TexCoordPrecision precision) const;
 };
 
 // Fragment shader for external textures.
 class FragmentShaderOESImageExternal : public FragmentTexAlphaBinding {
  public:
-  std::string GetShaderString() const;
+  std::string GetShaderString(TexCoordPrecision precision) const;
   bool Init(WebKit::WebGraphicsContext3D*,
             unsigned program,
             bool using_bind_uniform,
@@ -250,7 +266,7 @@ class FragmentShaderRGBATexAlphaAA {
             unsigned program,
             bool using_bind_uniform,
             int* base_uniform_index);
-  std::string GetShaderString() const;
+  std::string GetShaderString(TexCoordPrecision precision) const;
 
   int alpha_location() const { return alpha_location_; }
   int sampler_location() const { return sampler_location_; }
@@ -287,20 +303,20 @@ class FragmentTexClampAlphaAABinding {
 class FragmentShaderRGBATexClampAlphaAA :
   public FragmentTexClampAlphaAABinding {
  public:
-  std::string GetShaderString() const;
+  std::string GetShaderString(TexCoordPrecision precision) const;
 };
 
 // Swizzles the red and blue component of sampled texel.
 class FragmentShaderRGBATexClampSwizzleAlphaAA :
   public FragmentTexClampAlphaAABinding {
  public:
-  std::string GetShaderString() const;
+  std::string GetShaderString(TexCoordPrecision precision) const;
 };
 
 class FragmentShaderRGBATexAlphaMask {
  public:
   FragmentShaderRGBATexAlphaMask();
-  std::string GetShaderString() const;
+  std::string GetShaderString(TexCoordPrecision precision) const;
 
   void Init(WebKit::WebGraphicsContext3D*,
             unsigned program,
@@ -327,7 +343,7 @@ class FragmentShaderRGBATexAlphaMask {
 class FragmentShaderRGBATexAlphaMaskAA {
  public:
   FragmentShaderRGBATexAlphaMaskAA();
-  std::string GetShaderString() const;
+  std::string GetShaderString(TexCoordPrecision precision) const;
 
   void Init(WebKit::WebGraphicsContext3D*,
             unsigned program,
@@ -356,7 +372,7 @@ class FragmentShaderRGBATexAlphaMaskAA {
 class FragmentShaderYUVVideo {
  public:
   FragmentShaderYUVVideo();
-  std::string GetShaderString() const;
+  std::string GetShaderString(TexCoordPrecision precision) const;
 
   void Init(WebKit::WebGraphicsContext3D*,
             unsigned program,
@@ -381,7 +397,7 @@ class FragmentShaderYUVVideo {
 class FragmentShaderColor {
  public:
   FragmentShaderColor();
-  std::string GetShaderString() const;
+  std::string GetShaderString(TexCoordPrecision precision) const;
 
   void Init(WebKit::WebGraphicsContext3D*,
             unsigned program,
@@ -397,7 +413,7 @@ class FragmentShaderColor {
 class FragmentShaderColorAA {
  public:
   FragmentShaderColorAA();
-  std::string GetShaderString() const;
+  std::string GetShaderString(TexCoordPrecision precision) const;
 
   void Init(WebKit::WebGraphicsContext3D*,
             unsigned program,
@@ -414,7 +430,7 @@ class FragmentShaderColorAA {
 class FragmentShaderCheckerboard {
  public:
   FragmentShaderCheckerboard();
-  std::string GetShaderString() const;
+  std::string GetShaderString(TexCoordPrecision precision) const;
 
   void Init(WebKit::WebGraphicsContext3D*,
             unsigned program,