Avoid crashing when an ImageSkia has no representations and is converted to SkBitmap.

ui/gfx/image/image_skia.cc

 // Copyright (c) 2012 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 "ui/gfx/image/image_skia.h"
 
 #include <algorithm>
 #include <cmath>
 #include <limits>
 
@@ skipping 147 matching lines @@
 ImageSkia& ImageSkia::operator=(const ImageSkia& other) {
   storage_ = other.storage_;
   return *this;
 }
 
 ImageSkia& ImageSkia::operator=(const SkBitmap& other) {
   Init(ImageSkiaRep(other, ui::SCALE_FACTOR_100P));
   return *this;
 }
 
-ImageSkia::operator SkBitmap&() const {
-  if (isNull())
-    return const_cast<SkBitmap&>(NullImageRep().sk_bitmap());
-
-  return const_cast<SkBitmap&>(storage_->image_reps()[0].sk_bitmap());
-}
-
 ImageSkia::~ImageSkia() {
 }
 
 void ImageSkia::AddRepresentation(const ImageSkiaRep& image_rep) {
   DCHECK(!image_rep.is_null());
 
   if (isNull())
     Init(image_rep);
   else
     storage_->image_reps().push_back(image_rep);
@@ skipping 87 matching lines @@
   ImageSkiaReps image_reps;
   for (ImageSkiaReps::iterator it = internal_image_reps.begin();
        it != internal_image_reps.end(); ++it) {
     if (!it->is_null())
       image_reps.push_back(*it);
   }
 
   return image_reps;
 }
 
-const SkBitmap* ImageSkia::bitmap() const {
+ImageSkia::operator SkBitmap&() const {
   if (isNull()) {
     // Callers expect a ImageSkiaRep even if it is |isNull()|.
     // TODO(pkotwicz): Fix this.
-    return &NullImageRep().sk_bitmap();
+    return NullImageRep().mutable_sk_bitmap();
   }
 
   ImageSkiaReps::iterator it =
       storage_->FindRepresentation(ui::SCALE_FACTOR_100P, true);
-  return &it->sk_bitmap();
+  if (it != storage_->image_reps().end())
+    return it->mutable_sk_bitmap();
+  return NullImageRep().mutable_sk_bitmap();
 }
 
 void ImageSkia::Init(const ImageSkiaRep& image_rep) {
   // TODO(pkotwicz): The image should be null whenever image rep is null.
   if (image_rep.sk_bitmap().empty()) {
     storage_ = NULL;
     return;
   }
   storage_ = new internal::ImageSkiaStorage(
       NULL, gfx::Size(image_rep.GetWidth(), image_rep.GetHeight()));
   storage_->image_reps().push_back(image_rep);
 }
 
 }  // namespace gfx