Insert CHECK to look for abnormal flushes.

gpu/command_buffer/service/sync_point_manager.cc

 // 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 "gpu/command_buffer/service/sync_point_manager.h"
 
 #include <limits.h>
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 237 matching lines @@
     closure.Run();
   }
 }
 
 void SyncPointClientState::ReleaseFenceSyncLocked(
     uint64_t release,
     std::vector<base::Closure>* callback_list) {
   fence_sync_lock_.AssertAcquired();
   DCHECK_GT(release, fence_sync_release_);
 
+  // TODO(dyen): https://www.crbug.com/606112 - Hack in a DCHECK which should be
+  // fine under normal circumstances. Under normal usage, this would only
+  // trigger if flushes are arriving out of order.
+  CHECK(release == fence_sync_release_ + 1 || release == UINT64_MAX);
   fence_sync_release_ = release;
   while (!release_callback_queue_.empty() &&
          release_callback_queue_.top().release_count <= release) {
     callback_list->push_back(release_callback_queue_.top().callback_closure);
     release_callback_queue_.pop();
   }
 }
 
 void SyncPointClientState::SetOnWaitCallback(const OnWaitCallback& callback) {
   on_wait_callback_ = callback;
@@ skipping 151 matching lines @@
   DCHECK_LT(static_cast<size_t>(namespace_id), arraysize(client_maps_));
 
   base::AutoLock auto_lock(client_maps_lock_);
   ClientMap& client_map = client_maps_[namespace_id];
   ClientMap::iterator it = client_map.find(client_id);
   DCHECK(it != client_map.end());
   client_map.erase(it);
 }
 
 }  // namespace gpu