aura: A few changes to have aura_demo compile and run on linux.

ui/gfx/image/image.cc

 // Copyright (c) 2011 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.h"
 
 #include <algorithm>
 
 #include "base/logging.h"
 #include "base/stl_util.h"
@@ skipping 336 matching lines @@
 #endif
     CHECK(rep);
     AddRepresentation(rep);
     return rep;
   }
 
   // Handle Skia-to-native conversions.
   if (default_rep->type() == Image::kImageRepSkia) {
     internal::ImageRepSkia* skia_rep = default_rep->AsImageRepSkia();
     internal::ImageRep* native_rep = NULL;
-#if defined(TOOLKIT_USES_GTK)
+#if defined(USE_AURA)
+    skia_rep = NULL;
+    NOTIMPLEMENTED();
+#elif defined(TOOLKIT_USES_GTK)
     if (rep_type == Image::kImageRepGdk) {
       GdkPixbuf* pixbuf = gfx::GdkPixbufFromSkBitmap(skia_rep->bitmap());
       native_rep = new internal::ImageRepGdk(pixbuf);
     }
 #elif defined(OS_MACOSX)
     if (rep_type == Image::kImageRepCocoa) {
       NSImage* image = gfx::SkBitmapsToNSImage(skia_rep->bitmaps());
       base::mac::NSObjectRetain(image);
       native_rep = new internal::ImageRepCocoa(image);
     }
@@ skipping 15 matching lines @@
   return GetRepresentation(Image::kImageRepSkia)->AsImageRepSkia()->
       bitmaps().size();
 }
 
 const SkBitmap* Image::GetSkBitmapAtIndex(size_t index) const {
   return GetRepresentation(Image::kImageRepSkia)->AsImageRepSkia()->
       bitmaps()[index];
 }
 
 }  // namespace gfx