Plumb smooth scrolling in Chromium compositor

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 8f4a789b4948d97dd3116cc81d800a7923d53049..12696c730fbcc2469125cafba532550aefbd622c 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
@@ -1266,8 +1266,7 @@ public class ContentViewCore implements
     }
 
     public boolean isScrollInProgress() {
-        return mTouchScrollInProgress || mPotentiallyActiveFlingCount > 0
-                || getContentViewClient().isExternalScrollActive();
+        return mTouchScrollInProgress || mPotentiallyActiveFlingCount > 0;
     }
 
     @SuppressWarnings("unused")
@@ -1372,6 +1371,12 @@ public class ContentViewCore implements
         nativeDoubleTap(mNativeContentViewCore, timeMs, x, y);
     }
 
+    /**
+     * Flings the viewport with velocity vector (velocityX, velocityY).
+     * @param timeMs the current time.
+     * @param velocityX fling speed in x-axis.
+     * @param velocityY fling speed in y-axis.
+     */
     public void flingViewport(long timeMs, int velocityX, int velocityY) {
         if (mNativeContentViewCore == 0) return;
         nativeFlingCancel(mNativeContentViewCore, timeMs);
@@ -1420,9 +1425,6 @@ public class ContentViewCore implements
                             computeVerticalScrollOffset(),
                             computeVerticalScrollExtent());
                     break;
-                case GestureEventType.FLING_CANCEL:
-                    listener.onFlingCancelGesture();
-                    break;
                 case GestureEventType.SCROLL_START:
                     listener.onScrollStarted(
                             computeVerticalScrollOffset(),