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 4afd3a8b20a99a9cd4592aa9f6e296333bccf020..6fc872f552e883fe5f4a2edca8c98414b9409e71 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();
@@ -163,45 +179,45 @@ private:
 
 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 usingBindUniform, int* baseUniformIndex);
 private:
     int m_samplerLocation;
@@ -212,7 +228,7 @@ public:
     FragmentShaderRGBATexAlphaAA();
 
     void init(WebKit::WebGraphicsContext3D*, unsigned program, bool usingBindUniform, int* baseUniformIndex);
-    std::string getShaderString() const;
+    std::string getShaderString(TexCoordPrecision precision) const;
 
     int alphaLocation() const { return m_alphaLocation; }
     int samplerLocation() const { return m_samplerLocation; }
@@ -243,19 +259,19 @@ private:
 
 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, bool usingBindUniform, int* baseUniformIndex);
     int alphaLocation() const { return m_alphaLocation; }
@@ -275,7 +291,7 @@ private:
 class FragmentShaderRGBATexAlphaMaskAA {
 public:
     FragmentShaderRGBATexAlphaMaskAA();
-    std::string getShaderString() const;
+    std::string getShaderString(TexCoordPrecision precision) const;
 
     void init(WebKit::WebGraphicsContext3D*, unsigned program, bool usingBindUniform, int* baseUniformIndex);
     int alphaLocation() const { return m_alphaLocation; }
@@ -297,7 +313,7 @@ private:
 class FragmentShaderYUVVideo {
 public:
     FragmentShaderYUVVideo();
-    std::string getShaderString() const;
+    std::string getShaderString(TexCoordPrecision precision) const;
 
     void init(WebKit::WebGraphicsContext3D*, unsigned program, bool usingBindUniform, int* baseUniformIndex);
 
@@ -320,7 +336,7 @@ private:
 class FragmentShaderColor {
 public:
     FragmentShaderColor();
-    std::string getShaderString() const;
+    std::string getShaderString(TexCoordPrecision precision) const;
 
     void init(WebKit::WebGraphicsContext3D*, unsigned program, bool usingBindUniform, int* baseUniformIndex);
     int edgeLocation() const { return -1; }
@@ -333,7 +349,7 @@ private:
 class FragmentShaderColorAA {
 public:
     FragmentShaderColorAA();
-    std::string getShaderString() const;
+    std::string getShaderString(TexCoordPrecision precision) const;
 
     void init(WebKit::WebGraphicsContext3D*, unsigned program, bool usingBindUniform, int* baseUniformIndex);
     int edgeLocation() const { return m_edgeLocation; }
@@ -347,7 +363,7 @@ private:
 class FragmentShaderCheckerboard {
 public:
     FragmentShaderCheckerboard();
-    std::string getShaderString() const;
+    std::string getShaderString(TexCoordPrecision precision) const;
 
     void init(WebKit::WebGraphicsContext3D*, unsigned program, bool usingBindUniform, int* baseUniformIndex);
     int alphaLocation() const { return m_alphaLocation; }