Avoid unspecified behavior in SkiaBitmapDesktopFrame::Create

remoting/host/chromeos/skia_bitmap_desktop_frame.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 "base/logging.h"
 #include "remoting/host/chromeos/skia_bitmap_desktop_frame.h"
 
 namespace remoting {
 
 // static
 SkiaBitmapDesktopFrame* SkiaBitmapDesktopFrame::Create(
     scoped_ptr<SkBitmap> bitmap) {
 
   webrtc::DesktopSize size(bitmap->width(), bitmap->height());
   DCHECK_EQ(kBGRA_8888_SkColorType, bitmap->info().colorType())
       << "DesktopFrame objects always hold RGBA data.";
 
   bitmap->lockPixels();
   uint8_t* bitmap_data = reinterpret_cast<uint8_t*>(bitmap->getPixels());
   bitmap->unlockPixels();
 
+  const size_t row_bytes = bitmap->rowBytes();
   SkiaBitmapDesktopFrame* result = new SkiaBitmapDesktopFrame(
-      size, bitmap->rowBytes(), bitmap_data, bitmap.Pass());
+      size, row_bytes, bitmap_data, bitmap.Pass());
 
   return result;
 }
 
 SkiaBitmapDesktopFrame::SkiaBitmapDesktopFrame(webrtc::DesktopSize size,
                                                int stride,
                                                uint8_t* data,
                                                scoped_ptr<SkBitmap> bitmap)
     : DesktopFrame(size, stride, data, nullptr), bitmap_(bitmap.Pass()) {
 }
 
 SkiaBitmapDesktopFrame::~SkiaBitmapDesktopFrame() {
 }
 
 }  // namespace remoting