cc: Avoid posting renewTreePriority tasks with negative delay.

cc/thread_proxy.cc

 // Copyright 2011 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 "cc/thread_proxy.h"
 
 #include "base/auto_reset.h"
 #include "base/bind.h"
 #include "base/debug/trace_event.h"
 #include "cc/delay_based_time_source.h"
@@ skipping 1173 matching lines @@
     m_layerTreeHostImpl->setTreePriority(priority);
 
     // Notify the the client of this compositor via the output surface.
     // TODO(epenner): Route this to compositor-thread instead of output-surface
     // after GTFO refactor of compositor-thread (http://crbug/170828).
     if (m_layerTreeHostImpl->outputSurface()) {
         m_layerTreeHostImpl->outputSurface()->UpdateSmoothnessTakesPriority(
             priority == SMOOTHNESS_TAKES_PRIORITY);
     }
 
+    base::TimeDelta delay = m_smoothnessTakesPriorityExpirationTime -
+        base::TimeTicks::Now();
+
     // Need to make sure a delayed task is posted when we have smoothness
     // takes priority expiration time in the future.
-    if (m_smoothnessTakesPriorityExpirationTime <= base::TimeTicks::Now())
+    if (delay <= base::TimeDelta())
         return;
     if (m_renewTreePriorityOnImplThreadPending)
         return;
 
-    base::TimeDelta delay = m_smoothnessTakesPriorityExpirationTime -
-        base::TimeTicks::Now();
-
     Proxy::implThread()->postDelayedTask(
         base::Bind(&ThreadProxy::renewTreePriorityOnImplThread,
                    m_weakFactoryOnImplThread.GetWeakPtr()),
         delay.InMilliseconds());
 
     m_renewTreePriorityOnImplThreadPending = true;
 }
 
 void ThreadProxy::renewTreePriorityOnImplThread()
 {
     DCHECK(m_renewTreePriorityOnImplThreadPending);
     m_renewTreePriorityOnImplThreadPending = false;
 
     renewTreePriority();
 }
 
 }  // namespace cc