Make window message processing tally in the task profiler.

base/win/wrapped_window_proc.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Provides a way to handle exceptions that happen while a WindowProc is
 // running. The behavior of exceptions generated inside a WindowProc is OS
 // dependent, but it is possible that the OS just ignores the exception and
 // continues execution, which leads to unpredictable behavior for Chrome.
 
 #ifndef BASE_WIN_WRAPPED_WINDOW_PROC_H_
 #define BASE_WIN_WRAPPED_WINDOW_PROC_H_
 
 #include <windows.h>
 
 #include "base/base_export.h"
+#include "base/profiler/scoped_profile.h"
 #include "base/strings/string16.h"
 
 namespace base {
 namespace win {
 
 // An exception filter for a WindowProc. The return value determines how the
 // exception should be handled, following standard SEH rules. However, the
 // expected behavior for this function is to not return, instead of returning
 // EXCEPTION_EXECUTE_HANDLER or similar, given that in general we are not
 // prepared to handle exceptions.
@@ skipping 36 matching lines @@
 //
 //   WNDCLASSEX wc = {0};
 //   wc.lpfnWndProc = WrappedWindowProc<MyWinProc>;
 //   wc.lpszClassName = class_name;
 //   ...
 //   RegisterClassEx(&wc);
 //
 //   CreateWindowW(class_name, window_name, ...
 //
 template <WNDPROC proc>
-LRESULT CALLBACK WrappedWindowProc(HWND hwnd, UINT message,
-                                   WPARAM wparam, LPARAM lparam) {
+LRESULT CALLBACK ProfiledWrappedWindowProc(HWND hwnd,
+                                           UINT message,
+                                           WPARAM wparam,
+                                           LPARAM lparam) {
+  // The template parameter <proc> identifies the wrapped function.
+  tracked_objects::ScopedProfile scoped_profile(

[grt (UTC plus 2), 2017/05/16 07:27:35]

are you doing this in its own function template because stack unwinding won't
run dtors of stack objects within the scope of the __try{} in case of an
exception? if so, please document. if not, what is the benefit to this over
putting scoped_profile within the __try{} block?

i ask because with the two templates defined like this, i (the reader) wonder
why i would use WrappedWindowProc instead of ProfiledWrappedWindowProc. the
latter is the first thing i'll read, and sounds like a reasonable thing to use
("sure, i want profiling!").

[Sigurður Ásgeirsson, 2017/05/16 13:16:58]

This was pure habit - seems the ScopedProfile works just fine inside the __try
block.
The ScopedProfile won't get destructed on SEH, and this will mess up the
cumulatives for this thread, but it don't matter none, cause there's much bigger
problems, and the process isn't long for the world.

+      FROM_HERE, tracked_objects::ScopedProfile::ENABLED);
+
+  return proc(hwnd, message, wparam, lparam);
+}
+
+template <WNDPROC proc>
+LRESULT CALLBACK
+WrappedWindowProc(HWND hwnd, UINT message, WPARAM wparam, LPARAM lparam) {
   LRESULT rv = 0;
   __try {
-    rv = proc(hwnd, message, wparam, lparam);
+    rv = ProfiledWrappedWindowProc<proc>(hwnd, message, wparam, lparam);
   } __except(CallExceptionFilter(GetExceptionInformation())) {
   }
   return rv;
 }
 
 }  // namespace win
 }  // namespace base
 
 #endif  // BASE_WIN_WRAPPED_WINDOW_PROC_H_