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 7872b0762b1b16fdafa755579623a0d48203a03f..b350acfee977a632e6442960693158aab96fa2d4 100644
--- a/chrome/browser/ui/cocoa/browser_window_controller.mm
+++ b/chrome/browser/ui/cocoa/browser_window_controller.mm
@@ -1187,6 +1187,10 @@ 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.