Windows/Views: delete native bookmark manager code.

chrome/browser/cocoa/browser_window_cocoa.mm

Index: chrome/browser/cocoa/browser_window_cocoa.mm
diff --git a/chrome/browser/cocoa/browser_window_cocoa.mm b/chrome/browser/cocoa/browser_window_cocoa.mm
index 0de692f50082da36f1f8e887357d5fc2010b7136..1edee486b9084d6c68c6fbd19d084f2aa71ae930 100644
--- a/chrome/browser/cocoa/browser_window_cocoa.mm
+++ b/chrome/browser/cocoa/browser_window_cocoa.mm
@@ -264,11 +264,6 @@ void BrowserWindowCocoa::ShowTaskManager() {
   TaskManagerMac::Show();
 }
 
-void BrowserWindowCocoa::ShowBookmarkManager() {
-  // TODO(viettrungluu): Remove function when no callers remain. crbug.com/38908
-  NOTIMPLEMENTED();
-}
-
 void BrowserWindowCocoa::ShowBookmarkBubble(const GURL& url,
                                             bool already_bookmarked) {
   [controller_ showBookmarkBubbleForURL:url