Fix the URL status bubble overlapping the Mac download shelf

chrome/browser/cocoa/status_bubble_mac.h

 // 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.
 
 #ifndef CHROME_BROWSER_COCOA_STATUS_BUBBLE_MAC_H_
 #define CHROME_BROWSER_COCOA_STATUS_BUBBLE_MAC_H_
 
 #include <string>
 
 #import <Cocoa/Cocoa.h>
 
 #include "chrome/browser/status_bubble.h"
 
 class GURL;
 class StatusBubbleMacTest;
 
 class StatusBubbleMac : public StatusBubble {
  public:
-  StatusBubbleMac(NSWindow* parent);
+  StatusBubbleMac(NSWindow* parent, id delegate);
   virtual ~StatusBubbleMac();
 
   // StatusBubble implementation.
   virtual void SetStatus(const std::wstring& status);
   virtual void SetURL(const GURL& url, const std::wstring& languages);
   virtual void Hide();
   virtual void MouseMoved();
   virtual void UpdateDownloadShelfVisibility(bool visible);
 
  private:
   friend class StatusBubbleMacTest;
 
   void SetStatus(NSString* status, bool is_url);
 
   // Construct the window/widget if it does not already exist. (Safe to call if
   // it does.)
   void Create();
 
   void FadeIn();
   void FadeOut();
 
   // The window we attach ourselves to.
   NSWindow* parent_;  // WEAK
 
+  // The object that we query about our vertical offset for positioning.
+  id delegate_;  // WEAK
+
   // The window we own.
   NSWindow* window_;
 
   // The status text we want to display when there are no URLs to display.
   NSString* status_text_;
 
   // The url we want to display when there is no status text to display.
   NSString* url_text_;
 
   // How vertically offset the bubble is from its root position.
   int offset_;
+
+  // Is the download shelf visible.
+  bool is_download_shelf_visible_;
 };
 
+// Delegate interface that allows the StatusBubble to query its delegate about
+// the vertical offset (if any) that should be applied to the StatusBubble's
+// position.
+@interface NSObject(StatusBubbleDelegate)
+- (float)verticalOffsetForStatusBubble;
+@end
+
 #endif  // #ifndef CHROME_BROWSER_COCOA_STATUS_BUBBLE_MAC_H_