[Android] Provide synchronized input flush with BeginFrame

content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java

Index: content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
diff --git a/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java b/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
index 88785c177e4d7083df2badb0f07f756141072d1b..fa92f71f4490ee767d2dbde9554bbfdeac171d1b 100644
--- a/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
+++ b/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
@@ -293,7 +293,7 @@ import java.util.Map;
         };
 
         if (mVSyncSubscriberCount > 0) {
-            // setVSyncNotificationEnabled(true) is called before getVSyncListener.
+            // addVSyncSubscriber() is called before getVSyncListener.
             vsyncProvider.registerVSyncListener(mVSyncListener);
             mVSyncListenerRegistered = true;
         }
@@ -302,27 +302,35 @@ import java.util.Map;
     }
 
     @CalledByNative
-    void setVSyncNotificationEnabled(boolean enabled) {
-        if (!isVSyncNotificationEnabled() && enabled) {
+    void addVSyncSubscriber() {
+        if (!isVSyncNotificationEnabled()) {
             mDidSignalVSyncUsingInputEvent = false;
         }
         if (mVSyncProvider != null) {
-            if (!mVSyncListenerRegistered && enabled) {
+            if (!mVSyncListenerRegistered) {
                 mVSyncProvider.registerVSyncListener(mVSyncListener);
                 mVSyncListenerRegistered = true;
-            } else if (mVSyncSubscriberCount == 1 && !enabled) {
+            }
+        }
+        mVSyncSubscriberCount++;
+    }
+
+    @CalledByNative
+    void removeVSyncSubscriber() {
+        if (mVSyncProvider != null) {
+            if (mVSyncSubscriberCount == 1) {
                 assert mVSyncListenerRegistered;
                 mVSyncProvider.unregisterVSyncListener(mVSyncListener);
                 mVSyncListenerRegistered = false;
             }
         }
-        mVSyncSubscriberCount += enabled ? 1 : -1;
+        mVSyncSubscriberCount--;
         assert mVSyncSubscriberCount >= 0;
     }
 
     @CalledByNative
     private void resetVSyncNotification() {
-        while (isVSyncNotificationEnabled()) setVSyncNotificationEnabled(false);
+        while (isVSyncNotificationEnabled()) removeVSyncSubscriber();
         mVSyncSubscriberCount = 0;
         mVSyncListenerRegistered = false;
         mNeedAnimate = false;
@@ -336,7 +344,7 @@ import java.util.Map;
     private void setNeedsAnimate() {
         if (!mNeedAnimate) {
             mNeedAnimate = true;
-            setVSyncNotificationEnabled(true);
+            addVSyncSubscriber();
         }
     }
 
@@ -3096,7 +3104,7 @@ import java.util.Map;
     private void animateIfNecessary(long frameTimeMicros) {
         if (mNeedAnimate) {
             mNeedAnimate = onAnimate(frameTimeMicros);
-            if (!mNeedAnimate) setVSyncNotificationEnabled(false);
+            if (!mNeedAnimate) removeVSyncSubscriber();
         }
     }