extensions: Add ExtensionView interface.

chrome/browser/extensions/extension_view_container.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_EXTENSIONS_EXTENSION_VIEW_CONTAINER_H_
+#define CHROME_BROWSER_EXTENSIONS_EXTENSION_VIEW_CONTAINER_H_
+
+class ExtensionView;
+
+namespace gfx {
+class Size;
+}
+
+// A class that represents the container that this extension view is in.
+// (bottom shelf, side bar, etc.)
+class ExtensionViewContainer {
+ public:
+  virtual ~ExtensionViewContainer() {}
+
+  virtual void OnExtensionSizeChanged(ExtensionView* view,
+                                      const gfx::Size& new_size) = 0;
+
+  virtual void OnExtensionViewDidShow(ExtensionView* view) = 0;
+};
+
+#endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_VIEW_CONTAINER_H_