Add an "isInsideVSync" check.

ui/android/java/src/org/chromium/ui/base/WindowAndroid.java

Index: ui/android/java/src/org/chromium/ui/base/WindowAndroid.java
diff --git a/ui/android/java/src/org/chromium/ui/base/WindowAndroid.java b/ui/android/java/src/org/chromium/ui/base/WindowAndroid.java
index 424b566ed2430ff1863b524d0c67ca69aafd8a7a..6d3f3a6d1538a90ed7137b6f992c74610cfc56d8 100644
--- a/ui/android/java/src/org/chromium/ui/base/WindowAndroid.java
+++ b/ui/android/java/src/org/chromium/ui/base/WindowAndroid.java
@@ -57,6 +57,14 @@ public class WindowAndroid {
     };
 
     /**
+     * @return true if onVSync handler is executing.
+     * @see org.chromium.ui.VSyncMonitor#isInsideVSync().
+     */
+    public boolean isInsideVSync() {
+        return mVSyncMonitor.isInsideVSync();
+    }
+
+    /**
      * @param context The application context.
      */
     @SuppressLint("UseSparseArrays")