Make application shortcuts point to app_host.exe, install App Host during app installation.

chrome/browser/extensions/app_host_installer.cc

+// 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.
+
+#include "chrome/browser/extensions/app_host_installer.h"
+
+#include "base/bind.h"
+#include "base/callback.h"
+#include "base/logging.h"
+#include "base/process_util.h"
+#include "base/string16.h"
+#include "chrome/common/extensions/extension.h"

[benwells, 2012/10/04 07:53:01]

Nit: Move includes like string16, logging, process_util and browser_thread into
the #if.

[huangs, 2012/10/04 22:56:42]

Done.

+#include "content/public/browser/browser_thread.h"
+
+#if defined(OS_WIN)
+#include <windows.h>
+#include "base/win/object_watcher.h"
+#include "base/win/registry.h"
+#include "chrome/installer/launcher_support/chrome_launcher_support.h"
+#endif
+
+namespace {
+
+#if defined(OS_WIN)
+
+// TODO(huangs) Refactor the constants: http://crbug.com/148538
+const wchar_t kGoogleRegClientsKey[] = L"Software\\Google\\Update\\Clients";
+
+// Copied from chrome_appid.cc.
+const wchar_t kBinariesAppGuid[] = L"{4DC8B4CA-1BDA-483e-B5FA-D3C12E15B62D}";
+
+// Copied from google_update_constants.cc
+const wchar_t kRegCommandLineField[] = L"CommandLine";
+const wchar_t kRegCommandsKey[] = L"Commands";
+
+// Copied from util_constants.cc.
+const wchar_t kCmdQuickEnableApplicationHost[] =
+    L"quick-enable-application-host";
+
+class QuickEnableWatcher : public base::win::ObjectWatcher::Delegate {
+ public:
+  QuickEnableWatcher(const base::Callback<void(bool)>& callback)
+      : callback_(callback) {

[benwells, 2012/10/04 07:53:01]

Nit: {} (on one line)

[huangs, 2012/10/04 22:56:42]

Done.

+  }
+
+  // base::win::ObjectWatcher::Delegate implementation.
+  void OnObjectSignaled(HANDLE object) {

[erikwright (departed), 2012/10/04 01:28:16]

virtual ... OVERRIDE
#include compiler_specific

[huangs, 2012/10/04 22:56:42]

Done.

+    int exit_code = 0;
+    base::TerminationStatus status(

[benwells, 2012/10/04 07:53:01]

I'm not at all familiar withe ObjectWatcher. What happens if the process just
hangs and doesn't terminate? Is there some sort of timeout?

[huangs, 2012/10/04 22:56:42]

If process crashes, then it will return.  If it runs indefinitely, then there is
no timeout.

+        base::GetTerminationStatus(object, &exit_code));
+    if (status == base::TERMINATION_STATUS_NORMAL_TERMINATION) {
+      callback_.Run(true);
+    } else {
+      LOG(ERROR) << "App Host install failed, status = " << status
+                 << ", exit code = " << exit_code;
+      callback_.Run(false);
+    }
+    callback_.Reset();
+  }
+
+ private:
+  base::Callback<void(bool)> callback_;
+
+  DISALLOW_COPY_AND_ASSIGN(QuickEnableWatcher);
+};
+
+// Reads the path to app_host.exe from the value "UninstallString" within the
+// App Host's "ClientState" registry key.

[erikwright (departed), 2012/10/04 01:28:16]

"returns an empty string if the path does not exist or cannot be read."

[huangs, 2012/10/04 22:56:42]

Done.

+string16 GetQuickEnableAppHostCommand(bool system_level) {
+  HKEY root_key = system_level ? HKEY_LOCAL_MACHINE : HKEY_CURRENT_USER;
+  string16 subkey(kGoogleRegClientsKey);
+  subkey.append(1, L'\\').append(kBinariesAppGuid)
+      .append(1, L'\\').append(kRegCommandsKey)
+      .append(1, L'\\').append(kCmdQuickEnableApplicationHost);
+  base::win::RegKey reg_key;
+  string16 cmd;
+  if (reg_key.Open(root_key, subkey.c_str(),
+                   KEY_QUERY_VALUE) == ERROR_SUCCESS) {
+    // If read is unsuccessful, |cmd| remains empty.
+    reg_key.ReadValue(kRegCommandLineField, &cmd);
+  }
+  return cmd;
+}
+
+// Launches the Google Update command to quick-enable App Host.
+// Returns true if the command is launched.
+bool LaunchQuickEnableAppHost(base::win::ScopedHandle* process) {
+  DCHECK(!process->IsValid());
+  bool success = false;
+
+  string16 cmd_str(GetQuickEnableAppHostCommand(true));
+  if (cmd_str.empty()) {  // Try user-level if absent from system-level.
+    cmd_str = GetQuickEnableAppHostCommand(false);
+  }
+  if (!cmd_str.empty()) {
+    VLOG(1) << "Quick-enabling application host: " << cmd_str;
+    if (!base::LaunchProcess(cmd_str, base::LaunchOptions(),
+                             process->Receive())) {
+      LOG(ERROR) << "Failed to quick-enable application host.";
+    }
+    success = process->IsValid();
+  }
+  return success;
+}
+
+#endif
+
+}  // namespace
+
+namespace extensions {
+
+AppHostInstaller::AppHostInstaller() {

[benwells, 2012/10/04 07:53:01]

Nit: {}

[huangs, 2012/10/04 22:56:42]

Done.

+}
+
+// static
+bool AppHostInstaller::IsAppHostInstallRequired(const Extension& extension) {
+#if defined(OS_WIN)
+  return extension.is_platform_app() &&
+      !chrome_launcher_support::IsAppHostPresent();
+#else
+  return false;
+#endif
+}
+
+void AppHostInstaller::InstallAppHost(
+    const base::Callback<void(bool)>& callback) {
+#if defined(OS_WIN)
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::FILE));
+  DCHECK(!process_.IsValid());
+  if (FAILED(LaunchQuickEnableAppHost(&process_))) {

[erikwright (departed), 2012/10/04 01:28:16]

FAILED is for HRESULTS.

if (!Launch...()) {...}

[huangs, 2012/10/04 22:56:42]

Done.

+    callback.Run(false);
+  } else {
+    DCHECK(process_.IsValid());
+    DCHECK(!delegate_.get());
+    delegate_.reset(new QuickEnableWatcher(callback));

[erikwright (departed), 2012/10/04 01:28:16]

Although I think it's technically OK, I'd like to see the watcher_ stopped
before delegate_ is reset. At a glance, it looks as though the watcher could
reference the freed delegate somewhere between 135 and 136.

[huangs, 2012/10/04 22:56:42]

Done.

+    watcher_.StartWatching(process_, delegate_.get());
+  }
+#else
+  NOTREACHED() << "Attempt to install the App Host on an unsupported platform.";
+  callback.Run(false);
+#endif
+}
+
+}  // namespace extensions