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

chrome/browser/extensions/app_host_installer.cc

Index: chrome/browser/extensions/app_host_installer.cc
diff --git a/chrome/browser/extensions/app_host_installer.cc b/chrome/browser/extensions/app_host_installer.cc
new file mode 100644
index 0000000000000000000000000000000000000000..4bc8648c6ab756c089860884a45d6209c9ea6bc7
--- /dev/null
+++ b/chrome/browser/extensions/app_host_installer.cc
@@ -0,0 +1,267 @@
+// 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/compiler_specific.h"
+#include "chrome/common/extensions/extension.h"
+
+#if defined(OS_WIN)
+#include <windows.h>
+#include "base/logging.h"
+#include "base/process_util.h"
+#include "base/string16.h"
+#include "base/win/object_watcher.h"
+#include "base/win/registry.h"
+#include "chrome/installer/launcher_support/chrome_launcher_support.h"
+#include "content/public/browser/browser_thread.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) {}
+
+  // base::win::ObjectWatcher::Delegate implementation.
+  virtual void OnObjectSignaled(HANDLE object) OVERRIDE {
+    int exit_code = 0;
+    base::TerminationStatus status(
+        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.  Returns an empty string if the path
+// does not exist or cannot be read.
+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 {
+
+#if defined(OS_WIN)
+
+using content::BrowserThread;
+
+// App Host installation is necessary if
+//   (1) |extension| is platform app, and
+//   (2) app_host_exe is not installed.
+// Complexity arises because (1) can be checked from the caller thread,
+// but (2) must be checked in the FILE thread.
+// App Host installation is also launched in the FILE thread as an
+// asynchronous process.  Once installation completes, QuickEnableWatcher
+// is notified (on the FILE thread). This in turn notifies the caller thread
+// which then proceed with the next step specified by |final_step|.
+class AppHostInstallerImpl {

[erikwright (departed), 2012/10/05 02:21:56]

Move AppHostInstallerImpl to app_host_installer_impl_win.{h,cc}

[huangs, 2012/10/05 19:46:08]

Done.

+ public:
+  AppHostInstallerImpl();
+
+  // Implementation of AppHostInstaller::InstallAppHostIfNecessaryThenCall().
+  void InstallAppHostIfNecessaryThenCall(

[erikwright (departed), 2012/10/05 02:21:56]

Rename function and parameter.

"Implementation of" -> Implements

[huangs, 2012/10/05 19:46:08]

Done.

+      const Extension& extension,
+      const base::Callback<void(bool)>& final_step);
+
+ private:
+

[erikwright (departed), 2012/10/05 02:21:56]

remove blank line

[huangs, 2012/10/05 19:46:08]

Done.

+  // Runs on the FILE thread. Continues InstallAppHostIfNecessaryThenCall().
+  void InstallAppHostIfNecessaryOnFileThreadThenCall(

[erikwright (departed), 2012/10/05 02:21:56]

rename as elsewhere.

[huangs, 2012/10/05 19:46:08]

Done.

+      const base::Callback<void(bool)>& final_step);
+
+  // Runs on the FILE thread. Installs App Host, then calls
+  // |wrapped_final_step|.
+  void InstallAppHost(const base::Callback<void(bool)>& wrapped_final_step);
+
+  // Called from the FILE thread, to return to caller thread
+  // and call NotifyOnOriginalThread(), passing |final_step| and |result|.
+  void PostResultToCallerThread(BrowserThread::ID thread_id,

[erikwright (departed), 2012/10/05 02:21:56]

This method and the next one could actually be free functions in a private
namespace to simplify the class declaration.

[huangs, 2012/10/05 19:46:08]

Yes, but now it needs to be move elsewhere, which breaks the linear reading
flow.  But the function is removed anyway in the new flow.

+                                const base::Callback<void(bool)>& final_step,

[erikwright (departed), 2012/10/05 02:21:56]

final_step -> original_completion_callback

[huangs, 2012/10/05 19:46:08]

Moot in the new flow, since there is only one completion_callback now.

+                                bool result);
+
+  // Callback on the caller thread, to call |final_step| and pass |result|.
+  void NotifyOnOriginalThread(const base::Callback<void(bool)>& final_step,
+                              bool result);
+
+  base::win::ScopedHandle process_;
+  base::win::ObjectWatcher watcher_;
+  scoped_ptr<base::win::ObjectWatcher::Delegate> delegate_;
+
+ DISALLOW_COPY_AND_ASSIGN(AppHostInstallerImpl);
+};
+
+AppHostInstallerImpl::AppHostInstallerImpl() {}
+
+// (1) is checked here. If true, goes to FILE thread to proceed with (2),
+// else called |final_step| with true.
+void AppHostInstallerImpl::InstallAppHostIfNecessaryThenCall(
+    const Extension& extension,
+    const base::Callback<void(bool)>& final_step) {
+  if (extension.is_platform_app()) {
+    BrowserThread::ID caller_thread_id;
+    if (!BrowserThread::GetCurrentThreadIdentifier(&caller_thread_id)) {
+      NOTREACHED();
+    } else {
+      // Wrapping |final_step| with caller thread and the callback.
+      base::Callback<void(bool)> wrapped_final_step(
+          base::Bind(&AppHostInstallerImpl::PostResultToCallerThread,

[erikwright (departed), 2012/10/05 02:21:56]

Need a comment to explain why this callback can never be invoked after
AppHostInstallerImpl is destroyed.

[huangs, 2012/10/05 19:46:08]

Moot, since this is unused in the new flow.

+                     base::Unretained(this), caller_thread_id, final_step));
+      // Continue check (2) in FILE thread.
+      BrowserThread::PostTask(BrowserThread::FILE, FROM_HERE, base::Bind(
+          &AppHostInstallerImpl::InstallAppHostIfNecessaryOnFileThreadThenCall,
+          base::Unretained(this), wrapped_final_step));
+    }
+  } else {
+    final_step.Run(true);
+  }
+}
+
+// (2) is checked here. If false, calls |wrapped_final_step| and finish,
+// else install App Host.
+void AppHostInstallerImpl::InstallAppHostIfNecessaryOnFileThreadThenCall(
+    const base::Callback<void(bool)>& wrapped_final_step) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
+  if (chrome_launcher_support::IsAppHostPresent())
+    wrapped_final_step.Run(true);
+  else
+    InstallAppHost(wrapped_final_step);
+}
+
+// Main installation step, calls |wrapped_final_step| after.
+void AppHostInstallerImpl::InstallAppHost(
+    const base::Callback<void(bool)>& wrapped_final_step) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
+  DCHECK(!process_.IsValid());
+  if (!LaunchQuickEnableAppHost(&process_)) {
+    wrapped_final_step.Run(false);
+  } else {
+    DCHECK(process_.IsValid());
+    DCHECK(!delegate_.get());
+    watcher_.StopWatching();
+    delegate_.reset(new QuickEnableWatcher(wrapped_final_step));
+    watcher_.StartWatching(process_, delegate_.get());
+  }
+}
+
+// Destination of |wrapped_final_step|, invokes NotifyOnOriginalThread()
+// in the caller thread, passing |final_step| and |result|.
+void AppHostInstallerImpl::PostResultToCallerThread(
+    BrowserThread::ID thread_id,
+    const base::Callback<void(bool)>& final_step,
+    bool result) {
+  BrowserThread::PostTask(thread_id, FROM_HERE,
+      base::Bind(&AppHostInstallerImpl::NotifyOnOriginalThread,
+                 base::Unretained(this), final_step, result));
+}
+
+// Calls |final_step|, and passes |result| to complete flow.
+void AppHostInstallerImpl::NotifyOnOriginalThread(
+    const base::Callback<void(bool)>& final_step,
+    bool result) {
+  final_step.Run(result);
+}
+
+#else
+
+// Stub implementation for OS without App Host.
+class AppHostInstallerImpl {

[erikwright (departed), 2012/10/05 02:21:56]

No impl required in the else case - see below...

[huangs, 2012/10/05 19:46:08]

Done.

+ public:
+  AppHostInstallerImpl::AppHostInstallerImpl();
+
+  void AppHostInstallerImpl::InstallAppHostIfNecessaryThenCall(
+      const Extension& extension,
+      const base::Callback<void(bool)>& final_step);
+};
+
+AppHostInstallerImpl::AppHostInstallerImpl() {}
+
+void AppHostInstallerImpl::InstallAppHostIfNecessaryThenCall(
+    const Extension& extension,
+    const base::Callback<void(bool)>& final_step) {
+  final_step.Run(true);
+}
+
+#endif
+
+AppHostInstaller::AppHostInstaller() : impl_(new AppHostInstallerImpl()) {}

[erikwright (departed), 2012/10/05 02:21:56]

#if win, new AppHostInstallerImpl
#else 0

[huangs, 2012/10/05 19:46:08]

Done.

+
+AppHostInstaller::~AppHostInstaller() {
+  delete impl_;

[erikwright (departed), 2012/10/05 02:21:56]

if impl_
  delete impl_

[huangs, 2012/10/05 19:46:08]

Done.

+}
+
+void AppHostInstaller::InstallAppHostIfNecessaryThenCall(
+    const Extension& extension,
+    const base::Callback<void(bool)>& final_step) {
+  impl_->InstallAppHostIfNecessaryThenCall(extension, final_step);

[erikwright (departed), 2012/10/05 02:21:56]

if impl_
  impl_->...
else
  final_step.Run(true)

[huangs, 2012/10/05 19:46:08]

Done, but need to use #if define(OS_WIN), since we eliminated the stub
implementation.

+}
+
+}  // namespace extensions