gpu: Optimize and cleanup code used for CHROMIUM_copy_texture.

gpu/command_buffer/service/gles2_cmd_copy_texture_chromium.h

Index: gpu/command_buffer/service/gles2_cmd_copy_texture_chromium.h
diff --git a/gpu/command_buffer/service/gles2_cmd_copy_texture_chromium.h b/gpu/command_buffer/service/gles2_cmd_copy_texture_chromium.h
index 17290f8ed22f35fb2f8c69119a4e41af96a67a75..9a5c3e4a2ce95cc3426865e954d734785a4c7b6d 100644
--- a/gpu/command_buffer/service/gles2_cmd_copy_texture_chromium.h
+++ b/gpu/command_buffer/service/gles2_cmd_copy_texture_chromium.h
@@ -30,16 +30,17 @@ class GPU_EXPORT CopyTextureCHROMIUMResourceManager {
   void Destroy();
 
   void DoCopyTexture(const gles2::GLES2Decoder* decoder, GLenum source_target,
-                     GLenum dest_target, GLuint source_id, GLuint dest_id,
-                     GLint level, GLsizei width, GLsizei height,
+                     GLuint source_id, GLuint dest_id, GLint level,
+                     GLenum internal_format, GLsizei width, GLsizei height,
                      bool flip_y, bool premultiply_alpha,
                      bool unpremultiply_alpha);
 
   // This will apply a transform on the source texture before copying to
   // destination texture.
   void DoCopyTextureWithTransform(const gles2::GLES2Decoder* decoder,
-                                  GLenum source_target, GLenum dest_target,
-                                  GLuint source_id, GLuint dest_id, GLint level,
+                                  GLenum source_target, GLuint source_id,
+                                  GLuint dest_id, GLint level,
+                                  GLenum internal_format,
                                   GLsizei width, GLsizei height, bool flip_y,
                                   bool premultiply_alpha,
                                   bool unpremultiply_alpha,
@@ -49,6 +50,15 @@ class GPU_EXPORT CopyTextureCHROMIUMResourceManager {
   static const GLuint kVertexPositionAttrib = 0;
 
  private:
+  void DoFastCopyTexture(const gles2::GLES2Decoder* decoder,
+                         GLuint source_id,
+                         GLuint dest_id,
+                         GLint level,
+                         GLenum internal_format,
+                         GLsizei width,
+                         GLsizei height);

[reveman, 2014/07/09 19:45:08]

The name "DoFastCopyTexture" assumes that this is always faster. Can we use a
better name that doesn't make that assumption?

We probably have to add a setting to determine if this is faster or not and it
would be awkward if the name of that setting would need to be
"fast_copy_texture_is_faster" to match current naming...

Also, does this need to be a member function?

+  bool BindFramebufferTexture2D(GLuint texture_id, GLint level);

[reveman, 2014/07/09 19:45:08]

Does this need to be a member function? I'd prefer if you moved this to an
anonymous namespace in the .cc file if possible.

[dshwang, 2014/07/10 15:19:46]

Done. Only one reason is framebuffer_ member, but I moved it to anonymous
namespace.

+
   struct ProgramInfo {
     ProgramInfo()
         : program(0u),