Add RGB565 Texture readback support in gl_helper

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 90e9b7198e1cf2e2f42f51884643f38847b37c8b..383c26137b970c348eba5fbe375dd68b98722daf 100644
--- a/content/common/gpu/client/gl_helper.h
+++ b/content/common/gpu/client/gl_helper.h
@@ -181,6 +181,7 @@ class CONTENT_EXPORT GLHelper {
       const gfx::Rect& src_subrect,
       const gfx::Size& dst_size,
       unsigned char* out,
+      bool readback_config_rgb565,
       const base::Callback<void(bool)>& callback);
 
   // Copies the block of pixels specified with |src_subrect| from |src_mailbox|,
@@ -199,6 +200,7 @@ class CONTENT_EXPORT GLHelper {
       const gfx::Rect& src_subrect,
       const gfx::Size& dst_size,
       unsigned char* out,
+      bool readback_config_rgb565,
       const base::Callback<void(bool)>& callback);
 
   // Copies the texture data out of |texture| into |out|.  |size| is the
@@ -266,6 +268,9 @@ class CONTENT_EXPORT GLHelper {
   // size of the framebuffer.
   void CopyTextureFullImage(GLuint texture, const gfx::Size& size);
 
+  // Check whether rgb565 readback is supported or not.
+  bool CanUseRgb565Readback();
+
   // A scaler will cache all intermediate textures and programs
   // needed to scale from a specified size to a destination size.
   // If the source or destination sizes changes, you must create
@@ -326,6 +331,8 @@ class CONTENT_EXPORT GLHelper {
   gpu::ContextSupport* context_support_;
   scoped_ptr<CopyTextureToImpl> copy_texture_to_impl_;
   scoped_ptr<GLHelperScaling> scaler_impl_;
+  bool initialized_565_format_check_;
+  bool support_565_format_;
 
   DISALLOW_COPY_AND_ASSIGN(GLHelper);
 };