Enable texture readback support for Android

content/common/gpu/client/gl_helper.h

Index: content/common/gpu/client/gl_helper.h
diff --git a/content/common/gpu/client/gl_helper.h b/content/common/gpu/client/gl_helper.h
index 8157c9a96bed913ece6b6a2ceaa4ff35fc6c3f66..fd9f83a9cf047a49603cd9611d49d4e80105549a 100644
--- a/content/common/gpu/client/gl_helper.h
+++ b/content/common/gpu/client/gl_helper.h
@@ -30,19 +30,37 @@ class GLHelper {
 
   // Copies the block of pixels specified with |src_subrect| from |src_texture|,
   // scales it to |dst_size|, and writes it into |out|.
-  // |src_size| is the size of |src_texture|. |callback| is invoked with the
-  // copy result when the copy operation has completed.
-  void CopyTextureTo(WebKit::WebGLId src_texture,
-                     const gfx::Size& src_size,
-                     const gfx::Rect& src_subrect,
-                     const gfx::Size& dst_size,
-                     unsigned char* out,
-                     const base::Callback<void(bool)>& callback);
+  // |src_size| is the size of |src_texture|. The result is of format GL_BGRA
+  // and is potentially flipped vertically to make it a correct image
+  // representation.  |callback| is invoked with the copy result when the copy
+  // operation has completed.
+  void CropScaleReadbackAndCleanTexture(
+      WebKit::WebGLId src_texture,
+      const gfx::Size& src_size,
+      const gfx::Rect& src_subrect,
+      const gfx::Size& dst_size,
+      unsigned char* out,
+      const base::Callback<void(bool)>& callback);
+
+  // Copies the texture data out of |texture| into |out|.  |size| is the
+  // size of the texture.  No post processing is applied to the pixels.  The
+  // texture is assumed to have a format of GL_RGBA with a pixel type of
+  // GL_UNSIGNED_BYTE.  This is a blocking call that calls glReadPixels on this
+  // current context.
+  void ReadbackTextureSync(WebKit::WebGLId texture,
+                           const gfx::Size& size,
+                           unsigned char* out);
 
   // Creates a copy of the specified texture. |size| is the size of the texture.
   WebKit::WebGLId CopyTexture(WebKit::WebGLId texture,
                               const gfx::Size& size);
 
+  // Creates a scaled copy of the specified texture. |src_size| is the size of
+  // the texture and |dst_size| is the size of the resulting copy.
+  WebKit::WebGLId CopyAndScaleTexture(WebKit::WebGLId texture,
+                                      const gfx::Size& src_size,
+                                      const gfx::Size& dst_size);
+
   // Returns the shader compiled from the source.
   WebKit::WebGLId CompileShaderFromSource(const WebKit::WGC3Dchar* source,
                                           WebKit::WGC3Denum type);