Randomize sync point starting number to reduce risk of GPU hangs.

content/common/gpu/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 "content/common/gpu/sync_point_manager.h"
 
+#include <climits>
+
 #include "base/logging.h"
+#include "base/rand_util.h"
 
 namespace content {
 
+static const int kMaxSyncBase = INT_MAX;
+
 SyncPointManager::SyncPointManager()
-    : next_sync_point_(1) {
+    : next_sync_point_(base::RandInt(1, kMaxSyncBase)) {
+  // To reduce the risk that a sync point created in a previous GPU process
+  // will be in flight in the next GPU process, randomize the starting sync
+  // point number. http://crbug.com/373452
 }
 
 SyncPointManager::~SyncPointManager() {
 }
 
 uint32 SyncPointManager::GenerateSyncPoint() {
   base::AutoLock lock(lock_);
   uint32 sync_point = next_sync_point_++;
 
   // Note: wrapping would take days for a buggy/compromized renderer that would
@@ skipping 37 matching lines @@
 bool SyncPointManager::IsSyncPointRetired(uint32 sync_point) {
   DCHECK(thread_checker_.CalledOnValidThread());
   {
     base::AutoLock lock(lock_);
     SyncPointMap::iterator it = sync_point_map_.find(sync_point);
     return it == sync_point_map_.end();
   }
 }
 
 }  // namespace content