Remove burst mode from VSyncMonitor.

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

 // Copyright 2014 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.
 
 package org.chromium.ui;
 
 import android.annotation.SuppressLint;
 import android.content.Context;
 import android.os.Build;
 import android.os.Handler;
 import android.view.Choreographer;
 import android.view.WindowManager;
 
 import org.chromium.base.TraceEvent;
 
 /**
  * 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.
  */
 @SuppressLint("NewApi")
 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
      */
     public interface Listener {
         /**
          * Called very soon after the start of the display's vertical sync period.
          * @param monitor The VSyncMonitor that triggered the signal.
          * @param vsyncTimeMicros Absolute frame time in microseconds.
          */
         public void onVSync(VSyncMonitor monitor, long vsyncTimeMicros);
     }
 
     private Listener mListener;
 
     // Display refresh rate as reported by the system.
     private final long mRefreshPeriodNano;
 
     private boolean mHaveRequestInFlight;
-    private int mTriggerNextVSyncCount;
 
     // Choreographer is used to detect vsync on >= JB.
     private final Choreographer mChoreographer;
     private final Choreographer.FrameCallback mVSyncFrameCallback;
 
     // On ICS we just post a task through the handler (http://crbug.com/156397)
     private final Runnable mVSyncRunnableCallback;
     private long mGoodStartingPointNano;
     private long mLastPostedNano;
 
@@ skipping 17 matching lines @@
      * @param context The application context.
      * @param listener The listener receiving VSync notifications.
      * @param enableJBVsync Whether to allow Choreographer-based notifications on JB and up.
      */
     public VSyncMonitor(Context context, VSyncMonitor.Listener listener, boolean enableJBVSync) {
         mListener = listener;
         float refreshRate = ((WindowManager) context.getSystemService(Context.WINDOW_SERVICE))
                 .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.
             mChoreographer = Choreographer.getInstance();
             mVSyncFrameCallback = new Choreographer.FrameCallback() {
                 @Override
                 public void doFrame(long frameTimeNanos) {
                     TraceEvent.begin("VSync");
                     mGoodStartingPointNano = frameTimeNanos;
                     onVSyncCallback(frameTimeNanos, getCurrentNanoTime());
@@ skipping 36 matching lines @@
     }
 
     /**
      * Determine whether a true vsync signal is available on this platform.
      */
     private boolean isVSyncSignalAvailable() {
         return mChoreographer != null;
     }
 
     /**
      * Stop reporting vsync events. Note that at most one pending vsync event can still be delivered

[Sami, 2014/07/07 14:35:06]

Does this comment need updating? Do we need this function at all anymore?

[egor.starkov, 2014/07/07 15:08:59]

I left it here because was afraid to ruin some dependency code, that i don't
know about.

      * 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();
     }
 
     /**
      * Set the best guess of the point in the past when the vsync has happened.
      * @param goodStartingPointNano Known vsync point in the past.
      */
     public void setVSyncPointForICS(long goodStartingPointNano) {
         mGoodStartingPointNano = goodStartingPointNano;
     }
 
     private long getCurrentNanoTime() {
         return System.nanoTime();
     }
 
     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);
         }
     }
 
     private void postCallback() {
         if (mHaveRequestInFlight) return;
         mHaveRequestInFlight = true;
         if (postSyntheticVSync()) return;
         if (isVSyncSignalAvailable()) {
@@ skipping 28 matching lines @@
 
         if (currentTime + delay <= mLastPostedNano + mRefreshPeriodNano / 2) {
             delay += mRefreshPeriodNano;
         }
 
         mLastPostedNano = currentTime + delay;
         if (delay == 0) mHandler.post(mVSyncRunnableCallback);
         else mHandler.postDelayed(mVSyncRunnableCallback, delay / NANOSECONDS_PER_MILLISECOND);
     }
 }