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

chrome/browser/ui/cocoa/browser_window_controller.mm

Index: chrome/browser/ui/cocoa/browser_window_controller.mm
diff --git a/chrome/browser/ui/cocoa/browser_window_controller.mm b/chrome/browser/ui/cocoa/browser_window_controller.mm
index e003b0ee4e72d54f230f4c1e9464c80c43ca2c1e..dd675cba8de27232ecca7fa3263da3706956b828 100644
--- a/chrome/browser/ui/cocoa/browser_window_controller.mm
+++ b/chrome/browser/ui/cocoa/browser_window_controller.mm
@@ -1183,6 +1183,10 @@ enum {
   [toolbarController_ setStarredState:isStarred];
 }
 
+- (void)zoomChangedForActiveTab:(BOOL)canShowBubble {
+  [toolbarController_ zoomChangedForActiveTab:canShowBubble];
+}
+
 // Return the rect, in WebKit coordinates (flipped), of the window's grow box
 // in the coordinate system of the content area of the currently selected tab.
 // |windowGrowBox| needs to be in the window's coordinate system.