[Mac]Implement ViewID support.

chrome/browser/cocoa/extensions/browser_actions_container_view.mm

Index: chrome/browser/cocoa/extensions/browser_actions_container_view.mm
diff --git a/chrome/browser/cocoa/extensions/browser_actions_container_view.mm b/chrome/browser/cocoa/extensions/browser_actions_container_view.mm
index c417e8e427f86ddcb74965d76761c2a417ff6b92..5f78f86344b18f1955a717a0aa9537fa3bdb4573 100644
--- a/chrome/browser/cocoa/extensions/browser_actions_container_view.mm
+++ b/chrome/browser/cocoa/extensions/browser_actions_container_view.mm
@@ -8,6 +8,7 @@
 
 #include "base/logging.h"
 #import "base/scoped_nsobject.h"
+#import "chrome/browser/cocoa/view_id_util.h"
 
 NSString* const kBrowserActionGrippyDragStartedNotification =
     @"BrowserActionGrippyDragStartedNotification";
@@ -204,4 +205,9 @@ const CGFloat kUpperPadding = 9.0;
   return retVal;
 }
 
+// Tag is used solely for ViewID. Override to prevent changing of it.
+- (NSInteger)tag {
+  return view_id_util::ViewIDToTag(VIEW_ID_BROWSER_ACTION_TOOLBAR);
+}
+
 @end