[Fallback Icons] Refactor FallbackIconService to be a BrowserContext-level singleton

chrome/browser/ui/webui/large_icon_source.h

 // Copyright 2015 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.
 
 #ifndef CHROME_BROWSER_UI_WEBUI_LARGE_ICON_SOURCE_H_
 #define CHROME_BROWSER_UI_WEBUI_LARGE_ICON_SOURCE_H_
 
+#include <string>
+
 #include "base/memory/scoped_ptr.h"
 #include "base/task/cancelable_task_tracker.h"
 #include "components/favicon/core/fallback_icon_service.h"
 #include "components/favicon_base/favicon_types.h"
 #include "content/public/browser/url_data_source.h"
 
-class Profile;
+class FallbackIconService;
+class FaviconService;
 
 // LargeIconSource services explicit chrome:// requests for large icons.
 //
 // Format:
 //   chrome://large-icon/size/url
 //
 // Parameter:
 //  'size'             Required (including trailing '/')
 //    Positive integer to specify the large icon's size in pixels.
 //  'url'              Optional
 //    String to specify the page URL of the large icon.
 //
 //  Example: chrome://large-icon/48/http://www.google.com/
 //    This requests a 48x48 large icon for http://www.google.com.
 class LargeIconSource : public content::URLDataSource {
  public:
-  explicit LargeIconSource(Profile* profile);
+  // |favicon_service| and |fallback_icon_service| are owned by caller and may
+  // be null.
+  LargeIconSource(FaviconService* favicon_service,
+                  FallbackIconService* fallback_icon_service);
 
   ~LargeIconSource() override;
 
   // content::URLDataSource implementation.
   std::string GetSource() const override;
   void StartDataRequest(
       const std::string& path,
       int render_process_id,
       int render_frame_id,
       const content::URLDataSource::GotDataCallback& callback) override;
@@ skipping 20 matching lines @@
       const IconRequest& request,
       const favicon_base::FaviconRawBitmapResult& bitmap_result);
 
   // Renders and sends a fallback icon.
   void SendFallbackIcon(const IconRequest& request);
 
   // Returns null to trigger "Not Found" response.
   void SendNotFoundResponse(
       const content::URLDataSource::GotDataCallback& callback);
 
-  Profile* profile_;
-
   base::CancelableTaskTracker cancelable_task_tracker_;
 
-  scoped_ptr<FallbackIconService> fallback_icon_service_;
+  FaviconService* favicon_service_;
+
+  FallbackIconService* fallback_icon_service_;
 
   DISALLOW_COPY_AND_ASSIGN(LargeIconSource);
 };
 
 #endif  // CHROME_BROWSER_UI_WEBUI_LARGE_ICON_SOURCE_H_