Add super_onDrawVerticalScrollBar to WebView.PrivateAccess.
Add super_onDrawVerticalScrollBar to WebView.PrivateAccess.

This exposes the super_onDrawVerticalScrollBar method which will
be called by the WebViewChromium implementation.

Change-Id: I210dbab01c8b8d1eeff316a23c5d011e2e6c2a74

xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base