Make the UI an observer of downloads.

chrome/browser/ui/browser.h

 // 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.
 
 #ifndef CHROME_BROWSER_UI_BROWSER_H_
 #define CHROME_BROWSER_UI_BROWSER_H_
 
 #include <map>
 #include <set>
 #include <string>
@@ skipping 444 matching lines @@
 
   // Show the first run search engine bubble on the location bar.
   void ShowFirstRunBubble();
 
   // If necessary, update the bookmark bar state according to the Instant
   // overlay state: when Instant overlay shows suggestions and bookmark bar is
   // still showing attached, hide it.
   void MaybeUpdateBookmarkBarStateForInstantOverlay(
       const chrome::search::Mode& mode);
 
+  // Show a download on the download shelf.
+  void ShowDownload(content::DownloadItem* download);
+
   FullscreenController* fullscreen_controller() const {
     return fullscreen_controller_.get();
   }
 
   extensions::WindowController* extension_window_controller() const {
     return extension_window_controller_.get();
   }
 
  private:
   friend class BrowserTest;
@@ skipping 79 matching lines @@
   virtual bool TakeFocus(content::WebContents* source, bool reverse) OVERRIDE;
   virtual gfx::Rect GetRootWindowResizerRect() const OVERRIDE;
   virtual void BeforeUnloadFired(content::WebContents* source,
                                  bool proceed,
                                  bool* proceed_to_fire_unload) OVERRIDE;
   virtual bool ShouldFocusLocationBarByDefault(
       content::WebContents* source) OVERRIDE;
   virtual void SetFocusToLocationBar(bool select_all) OVERRIDE;
   virtual void RenderWidgetShowing() OVERRIDE;
   virtual int GetExtraRenderViewHeight() const OVERRIDE;
-  virtual void OnStartDownload(content::WebContents* source,
-                               content::DownloadItem* download) OVERRIDE;
   virtual void ViewSourceForTab(content::WebContents* source,
                                 const GURL& page_url) OVERRIDE;
   virtual void ViewSourceForFrame(
       content::WebContents* source,
       const GURL& frame_url,
       const std::string& frame_content_state) OVERRIDE;
   virtual void ShowRepostFormWarningDialog(
       content::WebContents* source) OVERRIDE;
   virtual bool ShouldCreateWebContents(
       content::WebContents* web_contents,
@@ skipping 351 matching lines @@
   bool window_has_shown_;
 
   // Currently open color chooser. Non-NULL after OpenColorChooser is called and
   // before DidEndColorChooser is called.
   scoped_ptr<content::ColorChooser> color_chooser_;
 
   DISALLOW_COPY_AND_ASSIGN(Browser);
 };
 
 #endif  // CHROME_BROWSER_UI_BROWSER_H_