Delay setting the compositor view background to null on N

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 a76f60aa2d00094b67427d489919d901efa2fe58..aa7d46f1db99e49be27846743de47d1863a5f278 100644
--- a/ui/android/java/src/org/chromium/ui/base/WindowAndroid.java
+++ b/ui/android/java/src/org/chromium/ui/base/WindowAndroid.java
@@ -155,6 +155,13 @@ public class WindowAndroid {
     }
 
     /**
+     * @return The time interval between two consecutive vsync pulses in milliseconds.
+     */
+    public long getVsyncPeriodInMillis() {

[Ted C, 2016/08/25 01:56:22]

it's odd these two methods are above the constructor but i guess it is
consistent with isInsideVsync.  We should move them down at some point

+        return mVSyncMonitor.getVSyncPeriodInMicroseconds() * 1000;
+    }
+
+    /**
      * @param context The application context.
      */
     @SuppressLint("UseSparseArrays")