[Ash] ShapedAppWindowTargeter treats empty shapes as empty hit test masks.

chrome/browser/ui/views/apps/shaped_app_window_targeter.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/views/apps/shaped_app_window_targeter.h"
 
 #include "chrome/browser/ui/views/apps/chrome_native_app_window_views.h"
 #include "ui/gfx/path.h"
 
 ShapedAppWindowTargeter::ShapedAppWindowTargeter(
     aura::Window* window,
     ChromeNativeAppWindowViews* app_window)
     : wm::MaskedWindowTargeter(window), app_window_(app_window) {}
 
 ShapedAppWindowTargeter::~ShapedAppWindowTargeter() {
 }
 
 bool ShapedAppWindowTargeter::GetHitTestMask(aura::Window* window,
                                              gfx::Path* mask) const {
   SkRegion* shape = app_window_->shape();
-  return shape ? shape->getBoundaryPath(mask) : false;
+  if (!shape)
+    return false;
+
+  shape->getBoundaryPath(mask);
+  return true;
 }