Register Application Restart with Windows Restart Manager

chrome/browser/browser_main_win.cc

Index: chrome/browser/browser_main_win.cc
diff --git a/chrome/browser/browser_main_win.cc b/chrome/browser/browser_main_win.cc
index cf5e78391ae5659d3b7bfa8f752d8398dacf0365..816154b70941c4ccb5cc2c24b54d941ca74857de 100644
--- a/chrome/browser/browser_main_win.cc
+++ b/chrome/browser/browser_main_win.cc
@@ -114,7 +114,7 @@ int DoUninstallTasks(bool chrome_still_running) {
 // the user if the browser process dies. These strings are stored in the
 // environment block so they are accessible in the early stages of the
 // chrome executable's lifetime.
-void PrepareRestartOnCrashEnviroment(const CommandLine &parsed_command_line) {
+void PrepareRestartOnCrashEnviroment(const CommandLine& parsed_command_line) {
   // Clear this var so child processes don't show the dialog by default.
   scoped_ptr<base::Environment> env(base::Environment::Create());
   env->UnSetVar(env_vars::kShowRestart);
@@ -146,11 +146,29 @@ void PrepareRestartOnCrashEnviroment(const CommandLine &parsed_command_line) {
   env->SetVar(env_vars::kRestartInfo, UTF16ToUTF8(dlg_strings));
 }
 
+bool RegisterApplicationRestart(const CommandLine& parsed_command_line) {
+  // The Windows Restart Manager expects a string of command line flags only,
+  // without the program.
+  CommandLine command_line(CommandLine::NO_PROGRAM);
+  command_line.AppendSwitches(parsed_command_line);
+  command_line.AppendArgs(parsed_command_line);
+  // Ensure restore last session is set.
+  if (!command_line.HasSwitch(switches::kRestoreLastSession))
+    command_line.AppendSwitch(switches::kRestoreLastSession);
+  const wchar_t *command_string = command_line.command_line_string().c_str();
+  // Restart Chrome if the computer is restarted as the result of an update.
+  // This could be extended to handle crashes, hangs, and patches.
+  HRESULT hr = ::RegisterApplicationRestart(command_string,

[Ben Goodger (Google), 2011/02/17 04:12:29]

One question: does this result in blocking I/O? (e.g. registry write?)

[Finnur, 2011/02/17 10:30:54]

FileMon shows no File/Registry access while executing this function call.

On 2011/02/17 04:12:29, Ben Goodger wrote:

[msw, 2011/02/17 12:18:29]

Short answer:
RegisterApplicationRestart() doesn't appear to perform a synchronous
registry/disk operation (although documentation is elusive), and PerfTimer
reports 0ms to execute. There are surprisingly thousands of registry/file ops by
Chrome on startup! I'll watch the startup perf dashboards closely after landing.

Long answer:
Using Process Monitor while running Chrome Debug via Visual Studio on Windows 7
shows 0 registry operations attributed to chrome.exe during
RegisterApplicationRestart(); the same is true for my test application. I don't
see any registry operations run by other processes during
RegisterApplicationRestart() that are obviously related to Chrome or Windows
Restart Manager. Regardless, Chrome apparently runs thousands of registry/file
operations on startup (see below), it's unlikely that several more would be
significant. All that said, I don't claim to have tremendous expertise here, and
these references allude to the Windows Restart Manager API itself using the
registry (msdn.microsoft.com/en-us/library/bb757039.aspx and ERROR_SEM_TIMEOUT
from RmGetList/RmShutdown/RmRestart via
msdn.microsoft.com/en-us/library/aa373649.aspx), although
RegisterApplicationRestart is listed separately as part of the "Supporting API".

Are we concerned that thousands of registry/file ops are performed during
startup? There are ~363 registry ops and ~900 file ops by Chrome.exe before
BrowserMain(). There are ~1968 *additional* registry ops and ~740 *additional*
file ops in BrowserMain() before browser_init.Start(). Altogether, I see ~12k
registry ops and ~6k file ops by chrome.exe during its first few seconds of
runtime.

+      RESTART_NO_CRASH | RESTART_NO_HANG | RESTART_NO_PATCH);
+  DCHECK(SUCCEEDED(hr)) << "RegisterApplicationRestart failed.";
+  return SUCCEEDED(hr);
+}
+
 // This method handles the --hide-icons and --show-icons command line options
 // for chrome that get triggered by Windows from registry entries
 // HideIconsCommand & ShowIconsCommand. Chrome doesn't support hide icons
 // functionality so we just ask the users if they want to uninstall Chrome.
-int HandleIconsCommands(const CommandLine &parsed_command_line) {
+int HandleIconsCommands(const CommandLine& parsed_command_line) {
   if (parsed_command_line.HasSwitch(switches::kHideIcons)) {
     string16 cp_applet;
     base::win::Version version = base::win::GetVersion();