Make channel preemption not require view contexts for hookup

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 65b0780bc52436dde66ae78b3d11f55ab233ab3a..5f793469757a0cd52b77e8ab2b7daa7c212248c1 100644
--- a/content/browser/renderer_host/render_widget_host_view_mac.mm
+++ b/content/browser/renderer_host/render_widget_host_view_mac.mm
@@ -1594,12 +1594,6 @@ gfx::Rect RenderWidgetHostViewMac::GetBoundsInRootWindow() {
   return FlipNSRectToRectScreen(bounds);
 }
 
-gfx::GLSurfaceHandle RenderWidgetHostViewMac::GetCompositingSurface() {
-  // TODO(kbr): may be able to eliminate PluginWindowHandle argument
-  // completely on Mac OS.
-  return gfx::GLSurfaceHandle(gfx::kNullPluginWindow, gfx::NULL_TRANSPORT);
-}
-
 bool RenderWidgetHostViewMac::LockMouse() {
   if (mouse_locked_)
     return true;