Plumb smooth scrolling in Chromium compositor

android_webview/java/src/org/chromium/android_webview/AwContents.java

Index: android_webview/java/src/org/chromium/android_webview/AwContents.java
diff --git a/android_webview/java/src/org/chromium/android_webview/AwContents.java b/android_webview/java/src/org/chromium/android_webview/AwContents.java
index 3b7a1654a3c6bef5b674c891f1e32949adcafc86..15b48c49d103444f73b7af5aa62e03c612840d30 100644
--- a/android_webview/java/src/org/chromium/android_webview/AwContents.java
+++ b/android_webview/java/src/org/chromium/android_webview/AwContents.java
@@ -40,7 +40,6 @@ import android.view.inputmethod.InputConnection;
 import android.webkit.GeolocationPermissions;
 import android.webkit.JavascriptInterface;
 import android.webkit.ValueCallback;
-import android.widget.OverScroller;
 
 import org.chromium.android_webview.permission.AwPermissionRequest;
 import org.chromium.base.CalledByNative;
@@ -188,8 +187,8 @@ public class AwContents implements SmartClipProvider,
         }
 
         public AwScrollOffsetManager createScrollOffsetManager(
-                AwScrollOffsetManager.Delegate delegate, OverScroller overScroller) {
-            return new AwScrollOffsetManager(delegate, overScroller);
+                AwScrollOffsetManager.Delegate delegate) {
+            return new AwScrollOffsetManager(delegate);
         }
     }
 
@@ -563,6 +562,12 @@ public class AwContents implements SmartClipProvider,
         }
 
         @Override
+        public void smoothScroll(
+                long currentMs, int startX, int startY, int dx, int dy, long durationMs) {
+            mContentViewCore.smoothScroll(currentMs, startX, startY, -dx, -dy, durationMs);
+        }
+
+        @Override
         public int getContainerViewScrollX() {
             return mContainerView.getScrollX();
         }
@@ -602,11 +607,6 @@ public class AwContents implements SmartClipProvider,
         }
 
         @Override
-        public void onFlingCancelGesture() {
-            mScrollOffsetManager.finishScroll();
-        }
-
-        @Override
         public void onScrollUpdateGestureConsumed() {
             mScrollAccessibilityHelper.postViewScrolledAccessibilityEventCallback();
         }
@@ -706,8 +706,8 @@ public class AwContents implements SmartClipProvider,
         mSettings.setDefaultVideoPosterURL(
                 mDefaultVideoPosterRequestHandler.getDefaultVideoPosterURL());
         mSettings.setDIPScale(mDIPScale);
-        mScrollOffsetManager = dependencyFactory.createScrollOffsetManager(
-                new AwScrollOffsetManagerDelegate(), new OverScroller(mContext));
+        mScrollOffsetManager =
+                dependencyFactory.createScrollOffsetManager(new AwScrollOffsetManagerDelegate());
         mScrollAccessibilityHelper = new ScrollAccessibilityHelper(mContainerView);
 
         setOverScrollMode(mContainerView.getOverScrollMode());
@@ -1949,13 +1949,6 @@ public class AwContents implements SmartClipProvider,
      */
     public void flingScroll(int velocityX, int velocityY) {
         if (TRACE) Log.d(TAG, "flingScroll");
-        // Cancel the current smooth scroll, if there is one.
-        mScrollOffsetManager.finishScroll();
-        // TODO(hush): crbug.com/493765. A hit test at 0, 0 may not
-        // target the scroll at root scrolling layer.  Instead, we
-        // should add a method flingRootLayer to ContentViewCore
-        // and call it here to specifically target the scroll at
-        // the root layer.
         mContentViewCore.flingViewport(SystemClock.uptimeMillis(), -velocityX, -velocityY);
     }
 
@@ -2573,11 +2566,6 @@ public class AwContents implements SmartClipProvider,
     }
 
     @CalledByNative
-    public boolean isSmoothScrollingActive() {
-        return mScrollOffsetManager.isSmoothScrollingActive();
-    }
-
-    @CalledByNative
     private void updateScrollState(int maxContainerViewScrollOffsetX,
             int maxContainerViewScrollOffsetY, int contentWidthDip, int contentHeightDip,
             float pageScaleFactor, float minPageScaleFactor, float maxPageScaleFactor) {
@@ -3020,13 +3008,8 @@ public class AwContents implements SmartClipProvider,
 
         @Override
         public void computeScroll() {
-            if (mScrollOffsetManager.isSmoothScrollingActive()) {
-                mScrollOffsetManager.computeScrollAndAbsorbGlow(mOverScrollGlow);
-            } else {
-                if (isDestroyed()) return;
-                nativeOnComputeScroll(
-                        mNativeAwContents, AnimationUtils.currentAnimationTimeMillis());
-            }
+            if (isDestroyed()) return;
+            nativeOnComputeScroll(mNativeAwContents, AnimationUtils.currentAnimationTimeMillis());
         }
     }