[Mac]Implement ViewID support.

chrome/browser/cocoa/browser_window_controller.mm

Index: chrome/browser/cocoa/browser_window_controller.mm
diff --git a/chrome/browser/cocoa/browser_window_controller.mm b/chrome/browser/cocoa/browser_window_controller.mm
index 1c5c681faa25c2e92ec9b286b4ea015258fb61be..2ea7b737d263876674f1c7a65ffbc9378171995a 100644
--- a/chrome/browser/cocoa/browser_window_controller.mm
+++ b/chrome/browser/cocoa/browser_window_controller.mm
@@ -918,7 +918,12 @@
     targetController = [[sender window] windowController];
   DCHECK([targetController isKindOfClass:[BrowserWindowController class]]);
   DCHECK(targetController->browser_.get());
-  targetController->browser_->ExecuteCommand([sender tag]);
+  NSInteger command;
+  if ([sender respondsToSelector:@selector(command)])
+    command = [sender command];
+  else
+    command = [sender tag];
+  targetController->browser_->ExecuteCommand(command);
 }
 
 // Same as |-commandDispatch:|, but executes commands using a disposition
@@ -931,7 +936,11 @@
   if ([sender respondsToSelector:@selector(window)])
     targetController = [[sender window] windowController];
   DCHECK([targetController isKindOfClass:[BrowserWindowController class]]);
-  NSInteger command = [sender tag];
+  NSInteger command;
+  if ([sender respondsToSelector:@selector(command)])
+    command = [sender command];
+  else
+    command = [sender tag];
   NSUInteger modifierFlags = [[NSApp currentEvent] modifierFlags];
   if ((command == IDC_RELOAD) && (modifierFlags & NSShiftKeyMask)) {
     command = IDC_RELOAD_IGNORING_CACHE;