Fix Up SingletonHwnd Observer Lifetime Issues

chrome/browser/extensions/global_shortcut_listener_win.cc

Index: chrome/browser/extensions/global_shortcut_listener_win.cc
diff --git a/chrome/browser/extensions/global_shortcut_listener_win.cc b/chrome/browser/extensions/global_shortcut_listener_win.cc
index 8f6f1912e36fc0b7a63893473c190c32798d1b9c..5d25c7ca0bad7b35aa681d9d597532cf65c5c097 100644
--- a/chrome/browser/extensions/global_shortcut_listener_win.cc
+++ b/chrome/browser/extensions/global_shortcut_listener_win.cc
@@ -4,6 +4,8 @@
 
 #include "chrome/browser/extensions/global_shortcut_listener_win.h"
 
+#include "base/bind.h"
+#include "base/bind_helpers.h"
 #include "base/win/win_util.h"
 #include "content/public/browser/browser_thread.h"
 #include "ui/base/accelerators/accelerator.h"
@@ -35,21 +37,22 @@ GlobalShortcutListenerWin::~GlobalShortcutListenerWin() {
 void GlobalShortcutListenerWin::StartListening() {
   DCHECK(!is_listening_);  // Don't start twice.
   DCHECK(!hotkey_ids_.empty());  // Also don't start if no hotkey is registered.
-  gfx::SingletonHwnd::GetInstance()->AddObserver(this);
+  singletonHwndObserver_.SetWndProc(
+      base::Bind(&GlobalShortcutListenerWin::OnHotkey, base::Unretained(this)));
   is_listening_ = true;
 }
 
 void GlobalShortcutListenerWin::StopListening() {
   DCHECK(is_listening_);  // No point if we are not already listening.
   DCHECK(hotkey_ids_.empty());  // Make sure the map is clean before ending.
-  gfx::SingletonHwnd::GetInstance()->RemoveObserver(this);
+  singletonHwndObserver_.ClearWndProc();
   is_listening_ = false;
 }
 
-void GlobalShortcutListenerWin::OnWndProc(HWND hwnd,
-                                          UINT message,
-                                          WPARAM wparam,
-                                          LPARAM lparam) {
+void GlobalShortcutListenerWin::OnHotkey(HWND hwnd,
+                                         UINT message,
+                                         WPARAM wparam,
+                                         LPARAM lparam) {
   if (message != WM_HOTKEY)
     return;