Fix mac raciness with initial needs begin frame state

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 433 matching lines @@
 // RenderWidgetHostViewMac, public:
 
 RenderWidgetHostViewMac::RenderWidgetHostViewMac(RenderWidgetHost* widget,
                                                  bool is_guest_view_hack)
     : render_widget_host_(RenderWidgetHostImpl::From(widget)),
       page_at_minimum_scale_(true),
       is_loading_(false),
       allow_pause_for_resize_or_repaint_(true),
       is_guest_view_hack_(is_guest_view_hack),
       fullscreen_parent_host_view_(nullptr),
-      needs_begin_frames_(false),
       needs_flush_input_(false),
       weak_factory_(this) {
   // |cocoa_view_| owns us and we will be deleted when |cocoa_view_|
   // goes away.  Since we autorelease it, our caller must put
   // |GetNativeView()| into the view hierarchy right after calling us.
   cocoa_view_ = [[[RenderWidgetHostViewCocoa alloc]
                   initWithRenderWidgetHostViewMac:this] autorelease];
 
   // Paint this view host with |background_color_| when there is no content
   // ready to draw.
@@ skipping 22 matching lines @@
 
   RenderViewHost* rvh = RenderViewHost::From(render_widget_host_);
   if (rvh) {
     // TODO(mostynb): actually use prefs.  Landing this as a separate CL
     // first to rebaseline some unreliable layout tests.
     ignore_result(rvh->GetWebkitPreferences());
   }
 
   if (GetTextInputManager())
     GetTextInputManager()->AddObserver(this);
+
+  // Because of the way Mac pumps messages during resize, (see the code
+  // in RenderMessageFilter::OnMessageReceived), SetNeedsBeginFrame
+  // messages are not delayed on Mac.  This leads to creation-time
+  // raciness where renderer sends a SetNeedsBeginFrame(true) before
+  // the renderer host is created to recieve it.  In general, all
+  // renderers want begin frames initially anyway, so start this value
+  // at true here to avoid startup raciness and decrease latency.
+  needs_begin_frames_ = true;
+  UpdateNeedsBeginFramesInternal();
 }
 
 RenderWidgetHostViewMac::~RenderWidgetHostViewMac() {
   display::Screen::GetScreen()->RemoveObserver(this);
 
   // This is being called from |cocoa_view_|'s destructor, so invalidate the
   // pointer.
   cocoa_view_ = nil;
 
   UnlockMouse();
@@ skipping 2905 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