Refactor browser window zoom handling and enable zoom icon on all platforms.

chrome/browser/ui/cocoa/location_bar/zoom_decoration.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_COCOA_LOCATION_BAR_ZOOM_DECORATION_H_
+#define CHROME_BROWSER_UI_COCOA_LOCATION_BAR_ZOOM_DECORATION_H_
+
+#import <Cocoa/Cocoa.h>
+
+#include "base/basictypes.h"
+#include "chrome/browser/ui/cocoa/location_bar/image_decoration.h"
+
+class ToolbarModel;
+class ZoomController;
+
+// Zoom icon at the end of the omnibox (close to page actions) when at a
+// non-standard zoom level.
+class ZoomDecoration : public ImageDecoration {
+ public:
+  explicit ZoomDecoration(ToolbarModel* toolbar_model);
+  virtual ~ZoomDecoration();
+
+  // Called when this decoration should show or hide itself in its most current
+  // state.
+  void Update(ZoomController* zoom_controller);
+
+ private:
+  // LocationBarDecoration implementation.
+  virtual NSString* GetToolTip() OVERRIDE;
+
+  // A reference to the toolbar model to query whether input is currently
+  // happening in the location bar. Not owned by this class.
+  ToolbarModel* toolbar_model_;
+
+  // The string to show for a tooltip.
+  scoped_nsobject<NSString> tooltip_;
+
+  DISALLOW_COPY_AND_ASSIGN(ZoomDecoration);
+};
+
+#endif  // CHROME_BROWSER_UI_COCOA_LOCATION_BAR_ZOOM_DECORATION_H_