ash: Fix crash in LaserPointerView::ReclaimResources.

ash/laser/laser_pointer_view.cc

 // Copyright 2016 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 "ash/laser/laser_pointer_view.h"
 
 #include <GLES2/gl2.h>
 #include <GLES2/gl2ext.h>
 #include <GLES2/gl2extchromium.h>
 
@@ skipping 420 matching lines @@
   base::TimeTicks next_presentation_time =
       ui::EventTimeForNow() + presentation_delay_;
   laser_points_.MoveForwardToTime(next_presentation_time);
   predicted_laser_points_.MoveForwardToTime(next_presentation_time);
   buffer_damage_rect_.Union(GetBoundingBox());
   OnPointsUpdated();
 }
 
 void LaserPointerView::DidReceiveCompositorFrameAck(
     const cc::ReturnedResourceArray& resources) {
-  ReclaimResources(resources);
+  if (!resources.empty())
+    ReclaimResources(resources);
 
   base::ThreadTaskRunnerHandle::Get()->PostTask(
       FROM_HERE, base::Bind(&LaserPointerView::OnDidDrawSurface,
                             weak_ptr_factory_.GetWeakPtr()));
 }
 
 void LaserPointerView::ReclaimResources(
     const cc::ReturnedResourceArray& resources) {
   DCHECK_EQ(resources.size(), 1u);
 
@@ skipping 312 matching lines @@
   pending_draw_surface_ = true;
 }
 
 void LaserPointerView::OnDidDrawSurface() {
   pending_draw_surface_ = false;
   if (needs_update_surface_)
     UpdateSurface();
 }
 
 }  // namespace ash