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 bac0560651b048f6a8b819a781ecf02f5c9eda04..8f96ff7b342486fdb708d51b9bf3d8a14f6e5270 100644
--- a/content/common/gpu/client/gl_helper.h
+++ b/content/common/gpu/client/gl_helper.h
@@ -214,7 +214,6 @@ class CONTENT_EXPORT GLHelper {
     SCALER_QUALITY_BEST = 3,
   };
 
-
   // 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|. The result is of format GL_BGRA
@@ -229,6 +228,7 @@ 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|,
@@ -247,6 +247,7 @@ 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
@@ -318,6 +319,9 @@ class CONTENT_EXPORT GLHelper {
   // size of the framebuffer.
   void CopyTextureFullImage(blink::WebGLId 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