Add RGB565 Texture readback support in gl_helper

content/browser/renderer_host/render_widget_host_view_gtk.cc

Index: content/browser/renderer_host/render_widget_host_view_gtk.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_gtk.cc b/content/browser/renderer_host/render_widget_host_view_gtk.cc
index e08e8d83d4d17709f242a850570215e25970dd09..b7d6e2e9ffd86f1b60e94ddeeaec4c4a362a0189 100644
--- a/content/browser/renderer_host/render_widget_host_view_gtk.cc
+++ b/content/browser/renderer_host/render_widget_host_view_gtk.cc
@@ -1047,7 +1047,12 @@ BackingStore* RenderWidgetHostViewGtk::AllocBackingStore(
 void RenderWidgetHostViewGtk::CopyFromCompositingSurface(
     const gfx::Rect& src_subrect,
     const gfx::Size& /* dst_size */,
-    const base::Callback<void(bool, const SkBitmap&)>& callback) {
+    const base::Callback<void(bool, const SkBitmap&)>& callback,
+    bool readback_config_rgb565) {
+  if (readback_config_rgb565) {
+    NOTIMPLEMENTED();
+    callback.Run(false, SkBitmap());
+  }
   // Grab the snapshot from the renderer as that's the only reliable way to
   // readback from the GPU for this platform right now.
   GetRenderWidgetHost()->GetSnapshotFromRenderer(src_subrect, callback);