mac: Don't set background color from a frame until frame is displayed

content/browser/renderer_host/render_widget_host_view_mac.mm

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/renderer_host/render_widget_host_view_mac.h"
 
 #import <Carbon/Carbon.h>
 #import <objc/runtime.h>
 #include <OpenGL/gl.h>
 #include <QuartzCore/QuartzCore.h>
@@ skipping 408 matching lines @@
 void RenderWidgetHostViewMac::AcceleratedWidgetGetVSyncParameters(
     base::TimeTicks* timebase, base::TimeDelta* interval) const {
   if (display_link_ &&
       display_link_->GetVSyncParameters(timebase, interval))
     return;
   *timebase = base::TimeTicks();
   *interval = base::TimeDelta();
 }
 
 void RenderWidgetHostViewMac::AcceleratedWidgetSwapCompleted() {
+  // Set the background color for the root layer from the frame that just
+  // swapped. See RenderWidgetHostViewAura for more details. Note that this is
+  // done only after the swap has completed, so that the background is not set
+  // before the frame is up.
+  UpdateBackgroundColorFromRenderer(last_frame_root_background_color_);
+
   if (display_link_)
     display_link_->NotifyCurrentTime(base::TimeTicks::Now());
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 // RenderWidgetHostViewMac, public:
 
 RenderWidgetHostViewMac::RenderWidgetHostViewMac(RenderWidgetHost* widget,
                                                  bool is_guest_view_hack)
     : render_widget_host_(RenderWidgetHostImpl::From(widget)),
@@ skipping 977 matching lines @@
     cc::mojom::MojoCompositorFrameSinkClient* renderer_compositor_frame_sink) {
   browser_compositor_->DidCreateNewRendererCompositorFrameSink(
       renderer_compositor_frame_sink);
 }
 
 void RenderWidgetHostViewMac::SubmitCompositorFrame(
     const cc::LocalSurfaceId& local_surface_id,
     cc::CompositorFrame frame) {
   TRACE_EVENT0("browser", "RenderWidgetHostViewMac::OnSwapCompositorFrame");
 
-  // Override the compositor background color. See RenderWidgetHostViewAura
-  // for more details.
-  UpdateBackgroundColorFromRenderer(frame.metadata.root_background_color);
-
+  last_frame_root_background_color_ = frame.metadata.root_background_color;
   last_scroll_offset_ = frame.metadata.root_scroll_offset;
 
   page_at_minimum_scale_ =
       frame.metadata.page_scale_factor == frame.metadata.min_page_scale_factor;
   browser_compositor_->SubmitCompositorFrame(local_surface_id,
                                              std::move(frame));
   UpdateDisplayVSyncParameters();
 }
 
 void RenderWidgetHostViewMac::OnBeginFrameDidNotSwap(
@@ skipping 2063 matching lines @@
 
 // "-webkit-app-region: drag | no-drag" is implemented on Mac by excluding
 // regions that are not draggable. (See ControlRegionView in
 // native_app_window_cocoa.mm). This requires the render host view to be
 // draggable by default.
 - (BOOL)mouseDownCanMoveWindow {
   return YES;
 }
 
 @end