Sometimes it's possible for a DOMUI to request images that don't exist (theme...

chrome/browser/dom_ui/dom_ui_theme_source.cc

 // Copyright (c) 2009 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/dom_ui/dom_ui_theme_source.h"
 
 #include "app/l10n_util.h"
 #include "app/resource_bundle.h"
 #include "app/theme_provider.h"
 #include "base/gfx/png_encoder.h"
@@ skipping 130 matching lines @@
 
   // Send.
   SendResponse(request_id, css_bytes);
 }
 
 void DOMUIThemeSource::SendThemeBitmap(int request_id, int resource_id) {
   ThemeProvider* tp = profile_->GetThemeProvider();
   DCHECK(tp);
 
   SkBitmap* image = tp->GetBitmapNamed(resource_id);
-  DCHECK(image);
+  if (!image || image->empty()) {
+    SendResponse(request_id, NULL);
+    return;
+  }
+
   std::vector<unsigned char> png_bytes;
   PNGEncoder::EncodeBGRASkBitmap(*image, false, &png_bytes);
 
   scoped_refptr<RefCountedBytes> image_data =
       new RefCountedBytes(png_bytes);
   SendResponse(request_id, image_data);
 }
 
 std::string DOMUIThemeSource::GetNewTabBackgroundCSS(bool bar_attached) {
   int alignment;
@@ skipping 21 matching lines @@
   return BrowserThemeProvider::AlignmentToString(alignment);
 }
 
 std::string DOMUIThemeSource::GetNewTabBackgroundTilingCSS() {
   int repeat_mode;
   profile_->GetThemeProvider()->GetDisplayProperty(
       BrowserThemeProvider::NTP_BACKGROUND_TILING, &repeat_mode);
   return BrowserThemeProvider::TilingToString(repeat_mode);
 }