Don't let RecyclerView consume fling action when there is no further space.

Before dispatch nested fling, check if there is any further space available
in the requested direction. If yes, set consumed to true; otherwise, false.
This can help list area in sharesheet responds to fling action to collapse.

Bug: 145998887
Test: manually tests. Fling down list area
will collapse sharesheet when list area reach its top edge; otherwise,
the list area itself will fling.

Change-Id: I060a1a91d6bdb0f3d6d0f825b065449223593bfc
diff --git a/core/java/com/android/internal/widget/RecyclerView.java b/core/java/com/android/internal/widget/RecyclerView.java
index b66a7b4..0f0ddbb 100644
--- a/core/java/com/android/internal/widget/RecyclerView.java
+++ b/core/java/com/android/internal/widget/RecyclerView.java
@@ -2011,13 +2011,27 @@
         }
 
         if (!dispatchNestedPreFling(velocityX, velocityY)) {
-            final boolean canScroll = canScrollHorizontal || canScrollVertical;
-            dispatchNestedFling(velocityX, velocityY, canScroll);
+            final View firstChild = mLayout.getChildAt(0);
+            final View lastChild = mLayout.getChildAt(mLayout.getChildCount() - 1);
+            boolean consumed = false;
+            if (velocityY < 0) {
+                consumed = getChildAdapterPosition(firstChild) > 0
+                        || firstChild.getTop() < getPaddingTop();
+            }
+
+            if (velocityY > 0) {
+                consumed = getChildAdapterPosition(lastChild) < mAdapter.getItemCount() - 1
+                        || lastChild.getBottom() > getHeight() - getPaddingBottom();
+            }
+
+            dispatchNestedFling(velocityX, velocityY, consumed);
 
             if (mOnFlingListener != null && mOnFlingListener.onFling(velocityX, velocityY)) {
                 return true;
             }
 
+            final boolean canScroll = canScrollHorizontal || canScrollVertical;
+
             if (canScroll) {
                 velocityX = Math.max(-mMaxFlingVelocity, Math.min(velocityX, mMaxFlingVelocity));
                 velocityY = Math.max(-mMaxFlingVelocity, Math.min(velocityY, mMaxFlingVelocity));