If Chrome Binaries version > App Host version, then update App Host.

chrome/installer/launcher_support/chrome_launcher_support.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/installer/launcher_support/chrome_launcher_support.h"
 
 #include <windows.h>
 #include <tchar.h>
 #include "base/file_path.h"
 #include "base/file_util.h"
+#include "base/logging.h"
 #ifndef OFFICIAL_BUILD
 #include "base/path_service.h"
 #endif
 #include "base/string16.h"
 #include "base/win/registry.h"
 
+namespace chrome_launcher_support {
+
 namespace {
 
-// TODO(erikwright): These constants are duplicated all over the place.
-// Consolidate them somehow.
-const wchar_t kChromeRegClientStateKey[] =
-    L"Software\\Google\\Update\\ClientState\\"
-    L"{8A69D345-D564-463c-AFF1-A69D9E530F96}";
+// TODO(huangs) Refactor the constants: http://crbug.com/148538
+const wchar_t kGoogleRegClientStateKey[] =
+    L"Software\\Google\\Update\\ClientState\\";
 
+// Copied from chrome_appid.cc.
+const wchar_t kBinariesAppGuid[] = L"{4DC8B4CA-1BDA-483e-B5FA-D3C12E15B62D}";
+
+// Copied from google_chrome_distribution.cc.
+const wchar_t kBrowserAppGuid[] = L"{8A69D345-D564-463c-AFF1-A69D9E530F96}";
+
+// Copied from util_constants.cc.
 const wchar_t kUninstallStringField[] = L"UninstallString";
-
 const wchar_t kChromeExe[] = L"chrome.exe";
 
 #ifndef OFFICIAL_BUILD
 FilePath GetDevelopmentChrome() {
   FilePath current_directory;
   if (PathService::Get(base::DIR_EXE, &current_directory)) {
     FilePath chrome_exe_path(current_directory.Append(kChromeExe));
     if (file_util::PathExists(chrome_exe_path))
       return chrome_exe_path;
   }
   return FilePath();
 }
 #endif
 
+// Reads the path to setup.exe from the value "UninstallString" within the
+// specified product's "ClientState" registry key. Returns an empty FilePath if
+// an error occurs or the product is not installed at the specified level.
+FilePath GetSetupExeFromRegistry(InstallationLevel level,
+                                 const wchar_t* app_guid) {
+  HKEY root_key = (level == USER_LEVEL_INSTALLATION) ?
+      HKEY_CURRENT_USER : HKEY_LOCAL_MACHINE;
+  string16 subkey(kGoogleRegClientStateKey);
+  subkey.append(app_guid);
+  base::win::RegKey reg_key;
+  if (reg_key.Open(root_key, subkey.c_str(),
+                   KEY_QUERY_VALUE) == ERROR_SUCCESS) {
+    string16 uninstall;
+    if (reg_key.ReadValue(kUninstallStringField, &uninstall) == ERROR_SUCCESS) {
+      FilePath setup_exe_path(uninstall);
+      if (file_util::PathExists(setup_exe_path))
+        return setup_exe_path;
+    }
+  }
+  return FilePath();
+}
+
 }  // namespace
 
-namespace chrome_launcher_support {
+FilePath GetSetupExeForInstallationLevel(InstallationLevel level) {
+  // Look in the registry for Chrome Binaries first.
+  FilePath setup_exe_path(GetSetupExeFromRegistry(level, kBinariesAppGuid));
+  // If the above fails, look in the registry for Chrome next.
+  if (setup_exe_path.empty())
+    setup_exe_path = GetSetupExeFromRegistry(level, kBrowserAppGuid);
+  // If we fail again, then setup_exe_path would be empty.
+  return setup_exe_path;
+}
+
+FilePath GetChromePathForInstallationLevel(InstallationLevel level) {
+  FilePath setup_exe_path(GetSetupExeForInstallationLevel(level));
+  if (!setup_exe_path.empty()) {
+    // The uninstall path contains the path to setup.exe which is two levels
+    // down from chrome.exe. Move up two levels (plus one to drop the file
+    // name) and look for chrome.exe from there.
+    FilePath chrome_exe_path(
+        setup_exe_path.DirName().DirName().DirName().Append(kChromeExe));
+    if (!file_util::PathExists(chrome_exe_path)) {
+      // By way of mild future proofing, look up one to see if there's a
+      // chrome.exe in the version directory
+      chrome_exe_path = chrome_exe_path.DirName().DirName().Append(kChromeExe);
+    }
+    if (file_util::PathExists(chrome_exe_path))
+      return chrome_exe_path;
+  }
+  return FilePath();
+}
 
 FilePath GetAnyChromePath() {
   FilePath chrome_path;
 #ifndef OFFICIAL_BUILD
   // For development mode, chrome.exe should be in same dir as the stub.
   chrome_path = GetDevelopmentChrome();
 #endif
   if (chrome_path.empty())
     chrome_path = GetChromePathForInstallationLevel(SYSTEM_LEVEL_INSTALLATION);
   if (chrome_path.empty())
     chrome_path = GetChromePathForInstallationLevel(USER_LEVEL_INSTALLATION);
-
   return chrome_path;
 }
 
-FilePath GetChromePathForInstallationLevel(InstallationLevel level) {
-  using base::win::RegKey;
-  HKEY root_key = (level == USER_LEVEL_INSTALLATION ?
-                   HKEY_CURRENT_USER :
-                   HKEY_LOCAL_MACHINE);
-  RegKey reg_key(root_key, kChromeRegClientStateKey, KEY_QUERY_VALUE);
-
-  FilePath chrome_exe_path;
-
-  if (reg_key.Valid()) {
-    // Now grab the uninstall string from the appropriate ClientState key
-    // and use that as the base for a path to chrome.exe.
-    string16 uninstall;
-    if (reg_key.ReadValue(kUninstallStringField, &uninstall) == ERROR_SUCCESS) {
-      // The uninstall path contains the path to setup.exe which is two levels
-      // down from chrome.exe. Move up two levels (plus one to drop the file
-      // name) and look for chrome.exe from there.
-      FilePath uninstall_path(uninstall);
-      chrome_exe_path =
-          uninstall_path.DirName().DirName().DirName().Append(kChromeExe);
-      if (!file_util::PathExists(chrome_exe_path)) {
-        // By way of mild future proofing, look up one to see if there's a
-        // chrome.exe in the version directory
-        chrome_exe_path =
-            uninstall_path.DirName().DirName().Append(kChromeExe);
-      }
-    }
-  }
-
-  if (file_util::PathExists(chrome_exe_path))
-    return chrome_exe_path;
-
-  return FilePath();
-}
-
 }  // namespace chrome_launcher_support