Remove some LazyInstance use in base/

base/win/message_window.cc

Index: base/win/message_window.cc
diff --git a/base/win/message_window.cc b/base/win/message_window.cc
index 26b64a533887e0e619d7b50a4d36f2de69d6303e..186377b5ae41e4925f203f128ce9b6bcfb3e9b48 100644
--- a/base/win/message_window.cc
+++ b/base/win/message_window.cc
@@ -4,7 +4,6 @@
 
 #include "base/win/message_window.h"
 
-#include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/win/current_module.h"
@@ -15,8 +14,8 @@ const wchar_t kMessageWindowClassName[] = L"Chrome_MessageWindow";
 namespace base {
 namespace win {
 
-// Used along with LazyInstance to register a window class for message-only
-// windows created by MessageWindow.
+// Used along with a threadsafe static pointer to register a window class for
+// message-only windows created by MessageWindow.
 class MessageWindow::WindowClass {
  public:
   WindowClass();
@@ -32,9 +31,6 @@ class MessageWindow::WindowClass {
   DISALLOW_COPY_AND_ASSIGN(WindowClass);
 };
 
-static LazyInstance<MessageWindow::WindowClass> g_window_class =

[Mark Mentovai, 2017/01/31 14:37:01]

This wasn’t leaky, and WindowClass has a destructor that does more than nothing.
How do you want to handle it?

[scottmg, 2017/01/31 18:19:16]

For general process shutdown, there's little point to UnregisterClass()ing, but
I guess the DCHECK potentially has some minor value in detecting leaks.

Hmm... I guess we might want a general helper function that either does both the
new'ing and OnExit() registration. But here, I think I'll just call
AtExitManager::RegisterCallback() for now, until we see how many non-leaky
things we truly want.

-    LAZY_INSTANCE_INITIALIZER;
-
 MessageWindow::WindowClass::WindowClass()
     : atom_(0), instance_(CURRENT_MODULE()) {
   WNDCLASSEX window_class;
@@ -104,9 +100,10 @@ bool MessageWindow::DoCreate(const MessageCallback& message_callback,
 
   message_callback_ = message_callback;
 
-  WindowClass& window_class = g_window_class.Get();
-  window_ = CreateWindow(MAKEINTATOM(window_class.atom()), window_name, 0, 0, 0,
-                         0, 0, HWND_MESSAGE, 0, window_class.instance(), this);
+  static auto window_class = new WindowClass();
+  window_ =
+      CreateWindow(MAKEINTATOM(window_class->atom()), window_name, 0, 0, 0, 0,
+                   0, HWND_MESSAGE, 0, window_class->instance(), this);
   if (!window_) {
     PLOG(ERROR) << "Failed to create a message-only window";
     return false;