Remove burst mode from VSyncMonitor.

Extra vsyncs after each rendering cause 1% more power consumption.

NOTRY=true

Review URL: https://codereview.chromium.org/346813002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@279997 0039d316-1c4b-4281-b951-d872f2087c98

AUTHORS

@@ -104,6 +104,7 @@ Douglas F. Turner <doug.turner@gmail.com>
 Eduardo Lima (Etrunko) <eduardo.lima@intel.com>
 Edward Crossman <tedoc2000@gmail.com>
 Eero Häkkinen <e.hakkinen@partner.samsung.com>
+Egor Starkov <egor.starkov@samsung.com>
 Ehsan Akhgari <ehsan.akhgari@gmail.com>
 Elan Ruusamäe <elan.ruusamae@gmail.com>
 Eric Ahn <byungwook.ahn@gmail.com>

content/public/android/javatests/src/org/chromium/content/browser/VSyncMonitorTest.java

@@ -82,7 +82,7 @@ public VSyncMonitor call() {
     private void performVSyncPeriodTest(boolean enableJBVSync) throws InterruptedException {
         // Collect roughly one second of data on a 60 fps display.
         collectAndCheckVSync(enableJBVSync, 60, true);
-        collectAndCheckVSync(enableJBVSync, VSyncMonitor.MAX_AUTO_ONVSYNC_COUNT, false);
+        collectAndCheckVSync(enableJBVSync, 60, false);
     }
 
     private void collectAndCheckVSync(

ui/android/java/src/org/chromium/ui/VSyncMonitor.java

@@ -15,9 +15,6 @@
 
 /**
  * Notifies clients of the default displays's vertical sync pulses.
- * This class works in "burst" mode: once the update is requested, the listener will be
- * called MAX_VSYNC_COUNT times on the vertical sync pulses (on JB) or on every refresh
- * period (on ICS, see below), unless stop() is called.
  * On ICS, VSyncMonitor relies on setVSyncPointForICS() being called to set a reasonable
  * approximation of a vertical sync starting point; see also http://crbug.com/156397.
  */
@@ -26,7 +23,6 @@ public class VSyncMonitor {
     private static final long NANOSECONDS_PER_SECOND = 1000000000;
     private static final long NANOSECONDS_PER_MILLISECOND = 1000000;
     private static final long NANOSECONDS_PER_MICROSECOND = 1000;
-    public static final int MAX_AUTO_ONVSYNC_COUNT = 5;
 
     /**
      * VSync listener class
@@ -46,7 +42,6 @@ public interface Listener {
     private final long mRefreshPeriodNano;
 
     private boolean mHaveRequestInFlight;
-    private int mTriggerNextVSyncCount;
 
     // Choreographer is used to detect vsync on >= JB.
     private final Choreographer mChoreographer;
@@ -84,7 +79,6 @@ public VSyncMonitor(Context context, VSyncMonitor.Listener listener, boolean ena
                 .getDefaultDisplay().getRefreshRate();
         if (refreshRate <= 0) refreshRate = 60;
         mRefreshPeriodNano = (long) (NANOSECONDS_PER_SECOND / refreshRate);
-        mTriggerNextVSyncCount = 0;
 
         if (enableJBVSync && Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
             // Use Choreographer on JB+ to get notified of vsync.
@@ -145,16 +139,13 @@ private boolean isVSyncSignalAvailable() {
      * after this function is called.
      */
     public void stop() {
-        mTriggerNextVSyncCount = 0;
     }
 
     /**
      * Request to be notified of the closest display vsync events.
      * Listener.onVSync() will be called soon after the upcoming vsync pulses.
-     * It will be called at most MAX_AUTO_ONVSYNC_COUNT times unless requestUpdate() is called.
      */
     public void requestUpdate() {
-        mTriggerNextVSyncCount = MAX_AUTO_ONVSYNC_COUNT;
         postCallback();
     }
 
@@ -174,10 +165,6 @@ private void onVSyncCallback(long frameTimeNanos, long currentTimeNanos) {
         assert mHaveRequestInFlight;
         mHaveRequestInFlight = false;
         mLastVSyncCpuTimeNano = currentTimeNanos;
-        if (mTriggerNextVSyncCount >= 0) {
-            mTriggerNextVSyncCount--;
-            postCallback();
-        }
         if (mListener != null) {
             mListener.onVSync(this, frameTimeNanos / NANOSECONDS_PER_MICROSECOND);
         }