Use the frame time from Choreographer for computeScroll animation time.

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

Index: ui/android/java/src/org/chromium/ui/VSyncMonitor.java
diff --git a/ui/android/java/src/org/chromium/ui/VSyncMonitor.java b/ui/android/java/src/org/chromium/ui/VSyncMonitor.java
index 281ed143c3f9299d42878f97486f7119d7292708..d43b040159af1a6b456a4c8330c0f8f3c8b2e4a6 100644
--- a/ui/android/java/src/org/chromium/ui/VSyncMonitor.java
+++ b/ui/android/java/src/org/chromium/ui/VSyncMonitor.java
@@ -17,6 +17,7 @@ import org.chromium.base.TraceEvent;
  */
 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;
 
     private boolean mInsideVSync = false;
@@ -116,6 +117,13 @@ public class VSyncMonitor {
         return mInsideVSync;
     }
 
+    /**
+     * @return the last VSync frame time in milli seconds.
+     */
+    public long getCurrentFrameTimeMillis() {
+        return mGoodStartingPointNano / NANOSECONDS_PER_MILLISECOND;
+    }
+
     private long getCurrentNanoTime() {
         return System.nanoTime();
     }