Revert 175275

cc/frame_rate_controller.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/frame_rate_controller.h"
 
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
 #include "cc/delay_based_time_source.h"
 #include "cc/time_source.h"
 #include "cc/thread.h"
 
+namespace {
+
+// This will be the maximum number of pending frames unless
+// FrameRateController::setMaxFramesPending is called.
+const int defaultMaxFramesPending = 2;
+
+}  // namespace
+
 namespace cc {
 
 class FrameRateControllerTimeSourceAdapter : public TimeSourceClient {
 public:
     static scoped_ptr<FrameRateControllerTimeSourceAdapter> create(FrameRateController* frameRateController) {
         return make_scoped_ptr(new FrameRateControllerTimeSourceAdapter(frameRateController));
     }
     virtual ~FrameRateControllerTimeSourceAdapter() {}
 
     virtual void onTimerTick() OVERRIDE {
       m_frameRateController->onTimerTick();
     }
 
 private:
     explicit FrameRateControllerTimeSourceAdapter(FrameRateController* frameRateController)
         : m_frameRateController(frameRateController) {}
 
     FrameRateController* m_frameRateController;
 };
 
 FrameRateController::FrameRateController(scoped_refptr<TimeSource> timer)
     : m_client(0)
     , m_numFramesPending(0)
-    , m_maxFramesPending(0)
+    , m_maxFramesPending(defaultMaxFramesPending)
     , m_timeSource(timer)
     , m_active(false)
     , m_swapBuffersCompleteSupported(true)
     , m_isTimeSourceThrottling(true)
     , m_thread(0)
     , m_weakFactory(ALLOW_THIS_IN_INITIALIZER_LIST(this))
 {
     m_timeSourceClientAdapter = FrameRateControllerTimeSourceAdapter::create(this);
     m_timeSource->setClient(m_timeSourceClientAdapter.get());
 }
 
 FrameRateController::FrameRateController(Thread* thread)
     : m_client(0)
     , m_numFramesPending(0)
-    , m_maxFramesPending(0)
+    , m_maxFramesPending(defaultMaxFramesPending)
     , m_active(false)
     , m_swapBuffersCompleteSupported(true)
     , m_isTimeSourceThrottling(false)
     , m_thread(thread)
     , m_weakFactory(ALLOW_THIS_IN_INITIALIZER_LIST(this))
 {
 }
 
 FrameRateController::~FrameRateController()
 {
@@ skipping 13 matching lines @@
     else {
         if (active)
             postManualTick();
         else
             m_weakFactory.InvalidateWeakPtrs();
     }
 }
 
 void FrameRateController::setMaxFramesPending(int maxFramesPending)
 {
-    DCHECK(maxFramesPending >= 0);
+    DCHECK(maxFramesPending > 0);
     m_maxFramesPending = maxFramesPending;
 }
 
 void FrameRateController::setTimebaseAndInterval(base::TimeTicks timebase, base::TimeDelta interval)
 {
     if (m_isTimeSourceThrottling)
         m_timeSource->setTimebaseAndInterval(timebase, interval);
 }
 
 void FrameRateController::setSwapBuffersCompleteSupported(bool supported)
 {
     m_swapBuffersCompleteSupported = supported;
 }
 
 void FrameRateController::onTimerTick()
 {
     DCHECK(m_active);
 
     // Check if we have too many frames in flight.
-    bool throttled = m_maxFramesPending && m_numFramesPending >= m_maxFramesPending;
+    bool throttled = m_numFramesPending >= m_maxFramesPending;
     TRACE_COUNTER_ID1("cc", "ThrottledVSyncInterval", m_thread, throttled);
 
     if (m_client)
         m_client->vsyncTick(throttled);
 
-    if (m_swapBuffersCompleteSupported && !m_isTimeSourceThrottling && !throttled)
+    if (m_swapBuffersCompleteSupported && !m_isTimeSourceThrottling && m_numFramesPending < m_maxFramesPending)
         postManualTick();
 }
 
 void FrameRateController::postManualTick()
 {
     if (m_active)
         m_thread->postTask(base::Bind(&FrameRateController::manualTick, m_weakFactory.GetWeakPtr()));
 }
 
 void FrameRateController::manualTick()
@@ skipping 25 matching lines @@
 
 base::TimeTicks FrameRateController::nextTickTime()
 {
     if (m_isTimeSourceThrottling)
         return m_timeSource->nextTickTime();
 
     return base::TimeTicks();
 }
 
 }  // namespace cc