Make sure we honor canChildScrollUp()

In the new nested scrolling flow we weren't
checking the callback. This CL adds it.

BUG: 25680804
Change-Id: I23cee7dde06b239195d02cd7ae7ab443b8769c36
diff --git a/v4/java/android/support/v4/widget/SwipeRefreshLayout.java b/v4/java/android/support/v4/widget/SwipeRefreshLayout.java
index e1386ab..18b762c 100644
--- a/v4/java/android/support/v4/widget/SwipeRefreshLayout.java
+++ b/v4/java/android/support/v4/widget/SwipeRefreshLayout.java
@@ -732,7 +732,7 @@
 
     @Override
     public boolean onStartNestedScroll(View child, View target, int nestedScrollAxes) {
-        return isEnabled() && !mReturningToStart && !mRefreshing
+        return isEnabled() && canChildScrollUp() && !mReturningToStart && !mRefreshing
                 && (nestedScrollAxes & ViewCompat.SCROLL_AXIS_VERTICAL) != 0;
     }