Make URLDataSource::GetSource() const.

chrome/browser/ui/webui/theme_source.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 "chrome/browser/ui/webui/theme_source.h"
 
 #include "base/memory/ref_counted_memory.h"
 #include "base/message_loop.h"
 #include "base/strings/string_number_conversions.h"
 #include "chrome/browser/profiles/profile.h"
@@ skipping 32 matching lines @@
 
 ThemeSource::ThemeSource(Profile* profile)
     : profile_(profile->GetOriginalProfile()) {
   css_bytes_ = NTPResourceCacheFactory::GetForProfile(profile)->GetNewTabCSS(
       profile->IsOffTheRecord());
 }
 
 ThemeSource::~ThemeSource() {
 }
 
-std::string ThemeSource::GetSource() {
+std::string ThemeSource::GetSource() const {
   return chrome::kChromeUIThemePath;
 }
 
 void ThemeSource::StartDataRequest(
     const std::string& path,
     bool is_incognito,
     const content::URLDataSource::GotDataCallback& callback) {
   // Default scale factor if not specified.
   ui::ScaleFactor scale_factor;
   std::string uncached_path;
@@ skipping 80 matching lines @@
 
     scoped_refptr<base::RefCountedMemory> image_data(tp->GetRawData(
         resource_id, scale_factor));
     callback.Run(image_data);
   } else {
     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
     const ResourceBundle& rb = ResourceBundle::GetSharedInstance();
     callback.Run(rb.LoadDataResourceBytesForScale(resource_id, scale_factor));
   }
 }