aw: Remove global AllowWait on UI thread

content/public/browser/android/synchronous_compositor.cc

 // Copyright 2016 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/public/browser/android/synchronous_compositor.h"
 
 #include <utility>
 
+#include "base/threading/thread_restrictions.h"
 #include "cc/output/compositor_frame.h"
 
 namespace content {
 
 SynchronousCompositor::Frame::Frame() : compositor_frame_sink_id(0u) {}
 
 SynchronousCompositor::Frame::~Frame() {}
 
 SynchronousCompositor::Frame::Frame(Frame&& rhs)
     : compositor_frame_sink_id(rhs.compositor_frame_sink_id),
@@ skipping 10 matching lines @@
   frame_ = std::move(frame);
   waitable_event_.Signal();
 }
 
 std::unique_ptr<SynchronousCompositor::Frame>
 SynchronousCompositor::FrameFuture::GetFrame() {
 #if DCHECK_IS_ON()
   DCHECK(!waited_);
   waited_ = true;
 #endif
+  base::ThreadRestrictions::ScopedAllowWait wait;
   waitable_event_.Wait();
   return std::move(frame_);
 }
 
 SynchronousCompositor::Frame& SynchronousCompositor::Frame::operator=(
     Frame&& rhs) {
   compositor_frame_sink_id = rhs.compositor_frame_sink_id;
   frame = std::move(rhs.frame);
   return *this;
 }
 
 }  // namespace content