Do not share a GL context between CoreAnimation and async readback

content/browser/renderer_host/compositing_iosurface_layer_mac.mm

 // Copyright 2013 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/compositing_iosurface_layer_mac.h"
 
 #include <CoreFoundation/CoreFoundation.h>
 #include <OpenGL/gl.h>
 
 #include "base/mac/sdk_forward_declarations.h"
 #include "content/browser/renderer_host/render_widget_host_impl.h"
 #include "content/browser/renderer_host/render_widget_host_view_mac.h"
 #include "content/browser/renderer_host/compositing_iosurface_context_mac.h"
 #include "content/browser/renderer_host/compositing_iosurface_mac.h"
 #include "ui/base/cocoa/animation_utils.h"
 #include "ui/gfx/size_conversions.h"
 #include "ui/gl/gpu_switching_manager.h"
 
 @implementation CompositingIOSurfaceLayer
 
 @synthesize context = context_;
 
 - (id)initWithRenderWidgetHostViewMac:(content::RenderWidgetHostViewMac*)r {
   if (self = [super init]) {
     renderWidgetHostView_ = r;
     context_ = content::CompositingIOSurfaceContext::Get(
-        content::CompositingIOSurfaceContext::kOffscreenContextWindowNumber);
+        content::CompositingIOSurfaceContext::kCALayerContextWindowNumber);
     DCHECK(context_);
     needsDisplay_ = NO;
 
     ScopedCAActionDisabler disabler;
     [self setBackgroundColor:CGColorGetConstantColor(kCGColorWhite)];
     [self setContentsGravity:kCAGravityTopLeft];
     [self setFrame:NSRectToCGRect(
         [renderWidgetHostView_->cocoa_view() bounds])];
     if ([self respondsToSelector:(@selector(setContentsScale:))]) {
       [self setContentsScale:
@@ skipping 117 matching lines @@
         false)) {
     renderWidgetHostView_->GotAcceleratedCompositingError();
     return;
   }
 
   needsDisplay_ = NO;
   renderWidgetHostView_->SendPendingLatencyInfoToHost();
 }
 
 @end