Revert of Add RGB565 Texture readback support in gl_helper

content/browser/renderer_host/render_widget_host_view_mac.mm

Index: content/browser/renderer_host/render_widget_host_view_mac.mm
diff --git a/content/browser/renderer_host/render_widget_host_view_mac.mm b/content/browser/renderer_host/render_widget_host_view_mac.mm
index 3b68caf048017dbeaa47060de9dec4bde6747114..5a4e688cae6fd6e9d855baea750b5c1765f568c3 100644
--- a/content/browser/renderer_host/render_widget_host_view_mac.mm
+++ b/content/browser/renderer_host/render_widget_host_view_mac.mm
@@ -1134,12 +1134,7 @@
 void RenderWidgetHostViewMac::CopyFromCompositingSurface(
     const gfx::Rect& src_subrect,
     const gfx::Size& dst_size,
-    const base::Callback<void(bool, const SkBitmap&)>& callback,
-    bool readback_config_rgb565) {
-  if (readback_config_rgb565) {
-    NOTIMPLEMENTED();
-    callback.Run(false, SkBitmap());
-  }
+    const base::Callback<void(bool, const SkBitmap&)>& callback) {
   base::ScopedClosureRunner scoped_callback_runner(
       base::Bind(callback, false, SkBitmap()));
   float scale = ScaleFactor(cocoa_view_);