Begin work on extension shelf for Linux.

chrome/browser/gtk/browser_window_gtk.h

Index: chrome/browser/gtk/browser_window_gtk.h
diff --git a/chrome/browser/gtk/browser_window_gtk.h b/chrome/browser/gtk/browser_window_gtk.h
index b15c9fcfb3557dbafd5c3b17eb7f34564d166e08..2040f92c2336b2fae3318dca8d5851680002d589 100644
--- a/chrome/browser/gtk/browser_window_gtk.h
+++ b/chrome/browser/gtk/browser_window_gtk.h
@@ -25,6 +25,7 @@ class BrowserTitlebar;
 class BrowserToolbarGtk;
 class CustomDrawButton;
 class DownloadShelfGtk;
+class ExtensionShelfGtk;
 class FindBarGtk;
 class InfoBarContainerGtk;
 class LocationBar;
@@ -179,6 +180,9 @@ class BrowserWindowGtk : public BrowserWindow,
   // Show or hide the bookmark bar.
   void MaybeShowBookmarkBar(TabContents* contents, bool animate);
 
+  // Show or hide the extension shelf.
+  void MaybeShowExtensionShelf();
+
   // Sets the default size for the window and the the way the user is allowed to
   // resize it.
   void SetGeometryHints();
@@ -254,6 +258,7 @@ class BrowserWindowGtk : public BrowserWindow,
   bool IsTabStripSupported();
   bool IsToolbarSupported();
   bool IsBookmarkBarSupported();
+  bool IsExtensionShelfSupported();
 
   // Checks to see if the mouse pointer at |x|, |y| is over the border of the
   // custom frame (a spot that should trigger a window resize). Returns true if
@@ -278,6 +283,9 @@ class BrowserWindowGtk : public BrowserWindow,
   // The object that manages the bookmark bar.
   scoped_ptr<BookmarkBarGtk> bookmark_bar_;
 
+  // The object that manages the extension shelf.
+  scoped_ptr<ExtensionShelfGtk> extension_shelf_;
+
   // The status bubble manager.  Always non-NULL.
   scoped_ptr<StatusBubbleGtk> status_bubble_;