Split the singleton hwnd from screen_compatible_dc_win.cc.

ui/gfx/screen_compatible_dc_win.cc

Index: ui/gfx/screen_compatible_dc_win.cc
===================================================================
--- ui/gfx/screen_compatible_dc_win.cc	(revision 120986)
+++ ui/gfx/screen_compatible_dc_win.cc	(working copy)
@@ -4,16 +4,15 @@
 
 #include "ui/gfx/screen_compatible_dc_win.h"
 
+#include "base/bind.h"
+#include "base/callback.h"
 #include "base/logging.h"
 #include "base/memory/singleton.h"
 #include "base/win/wrapped_window_proc.h"
-#include "ui/base/win/hwnd_util.h"
+#include "ui/base/win/singleton_hwnd.h"
 
 namespace {
 
-// Windows class name to use for the listener window.
-const wchar_t kWindowClassName[] = L"CachedCompatibleDC_Invalidator";
-
 class CachedCompatibleDC {
  public:
   // Singleton getter.
@@ -22,6 +21,9 @@
   // Returns the cached screen compatible DC or creates one if needed.
   HDC GetOrCreateCompatibleDC();
 
+  // Listener for WM_DISPLAYCHANGE notifications.
+  void OnWndProc(HWND hwnd, UINT message, WPARAM wparam, LPARAM lparam);
+
   // Deletes the cached DC, called on WM_DISPLAYCHANGE notifications.
   void DeleteCachedCompatibleDC();
 
@@ -29,8 +31,8 @@
   // Cached device context compatible with the screen.
   HDC compatible_dc_;
 
-  // HWND for listening to WM_DISPLAYCHANGE notifications.
-  HWND listener_window_;
+  // Indicates whether the listener has been registered with the SingletonHwnd.
+  bool listener_registered_;
 
   CachedCompatibleDC();
   ~CachedCompatibleDC();
@@ -40,49 +42,13 @@
   DISALLOW_COPY_AND_ASSIGN(CachedCompatibleDC);
 };
 
-// Windows callback for listening for WM_DISPLAYCHANGE messages.
-LRESULT CALLBACK ListenerWindowProc(HWND hwnd,
-                                    UINT message,
-                                    WPARAM wparam,
-                                    LPARAM lparam) {
-  if (message == WM_DISPLAYCHANGE)
-    CachedCompatibleDC::GetInstance()->DeleteCachedCompatibleDC();
-
-  return ::DefWindowProc(hwnd, message, wparam, lparam);
-}
-
-// Creates a listener window to handle WM_DISPLAYCHANGE messages.
-HWND CreateListenerWindow() {
-  HINSTANCE hinst = 0;
-  if (!::GetModuleHandleExA(GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS,
-                            reinterpret_cast<char*>(&ListenerWindowProc),
-                            &hinst)) {
-    NOTREACHED();
-  }
-
-  WNDCLASSEX wc = {0};
-  wc.cbSize = sizeof(wc);
-  wc.lpfnWndProc = base::win::WrappedWindowProc<ListenerWindowProc>;
-  wc.hInstance = hinst;
-  wc.lpszClassName = kWindowClassName;
-  ATOM clazz = ::RegisterClassEx(&wc);
-  DCHECK(clazz);
-
-  return ::CreateWindow(MAKEINTATOM(clazz), 0, 0, 0, 0, 0, 0, HWND_MESSAGE, 0,
-                        hinst, 0);
-}
-
 CachedCompatibleDC::CachedCompatibleDC()
     : compatible_dc_(NULL),
-      listener_window_(NULL) {
+      listener_registered_(false) {
 }
 
 CachedCompatibleDC::~CachedCompatibleDC() {
   DeleteCachedCompatibleDC();
-  if (listener_window_) {
-    ::DestroyWindow(listener_window_);
-    ::UnregisterClass(kWindowClassName, GetModuleHandle(NULL));
-  }
 }
 
 // static
@@ -93,14 +59,24 @@
 HDC CachedCompatibleDC::GetOrCreateCompatibleDC() {
   if (!compatible_dc_) {
     compatible_dc_ = ::CreateCompatibleDC(NULL);
-    if (!listener_window_) {
-      listener_window_ = CreateListenerWindow();
-      ui::CheckWindowCreated(listener_window_);
+    if (!listener_registered_) {
+      ui::WndProcCallback callback =
+          base::Bind(&CachedCompatibleDC::OnWndProc, base::Unretained(this));
+      ui::SingletonHwnd::GetInstance()->RegisterListener(callback);
+      listener_registered_ = true;
     }
   }
   return compatible_dc_;
 }
 
+void CachedCompatibleDC::OnWndProc(HWND hwnd,
+                                   UINT message,
+                                   WPARAM wparam,
+                                   LPARAM lparam) {
+  if (message == WM_DISPLAYCHANGE)
+    DeleteCachedCompatibleDC();
+}
+
 void CachedCompatibleDC::DeleteCachedCompatibleDC() {
   if (compatible_dc_) {
     ::DeleteDC(compatible_dc_);