Always invalidate whole NSView when switching to GPU mode

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"
 
 #include <QuartzCore/QuartzCore.h>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 1219 matching lines @@
   render_widget_host_->Shutdown();
   // Do not touch any members at this point, |this| has been deleted.
 }
 
 void RenderWidgetHostViewMac::GotAcceleratedFrame() {
   if (!last_frame_was_accelerated_) {
     last_frame_was_accelerated_ = true;
 
     // Need to wipe the software view with transparency to expose the GL
     // underlay. Invalidate the whole window to do that.
-    if (!about_to_validate_and_paint_)
-      [cocoa_view_ setNeedsDisplay:YES];
+    [cocoa_view_ setNeedsDisplay:YES];
 
     // Delete software backingstore.
     BackingStoreManager::RemoveBackingStore(render_widget_host_);
   }
 }
 
 void RenderWidgetHostViewMac::GotSoftwareFrame() {
   if (last_frame_was_accelerated_) {
     last_frame_was_accelerated_ = false;
 
@@ skipping 1840 matching lines @@
   if (!string) return NO;
 
   // If the user is currently using an IME, confirm the IME input,
   // and then insert the text from the service, the same as TextEdit and Safari.
   [self confirmComposition];
   [self insertText:string];
   return YES;
 }
 
 @end