Give SxS distribution its own registration GUIDs.

chrome/installer/util/install_util.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.
 //
 // See the corresponding header file for description of the functions in this
 // file.
 
 #include "chrome/installer/util/install_util.h"
 
 #include <shellapi.h>
@@ skipping 347 matching lines @@
   CHECK(command_line);
 
   if (command_line->HasSwitch(installer::switches::kChromeSxS))
     return true;
 
   // Also return true if we are running from Chrome SxS installed path.
   base::FilePath exe_dir;
   PathService::Get(base::DIR_EXE, &exe_dir);
   string16 chrome_sxs_dir(installer::kGoogleChromeInstallSubDir2);
   chrome_sxs_dir.append(installer::kSxSSuffix);
-  return base::FilePath::CompareEqualIgnoreCase(
-          exe_dir.BaseName().value(), installer::kInstallBinaryDir) &&
-      base::FilePath::CompareEqualIgnoreCase(
-          exe_dir.DirName().BaseName().value(), chrome_sxs_dir);
+
+  // This is SxS if current EXE is in or under (possibly multiple levels under)
+  // |chrome_sxs_dir|\|installer::kInstallBinaryDir|
+  std::vector<base::FilePath::StringType> components;
+  exe_dir.GetComponents(&components);
+  auto iter = components.rbegin();

[grt (UTC plus 2), 2013/09/09 18:39:15]

i don't believe auto is approved for use yet. please either drop its use, or
show me what i missed.

+  while (iter != components.rend()) {
+    auto next = iter+1;
+
+    if (base::FilePath::CompareEqualIgnoreCase(*iter,
+        installer::kInstallBinaryDir)) {
+
+      if (next != components.rend() &&
+          (base::FilePath::CompareEqualIgnoreCase(*next, chrome_sxs_dir)))
+        return true;
+    }
+
+    iter = next;
+  }
+
+  return false;
 }
 
 bool InstallUtil::IsChromeSxSProcess() {
   static bool sxs = CheckIsChromeSxSProcess();
   return sxs;
 }
 
 bool InstallUtil::GetSentinelFilePath(const base::FilePath::CharType* file,
                                       BrowserDistribution* dist,
                                       base::FilePath* path) {
@@ skipping 221 matching lines @@
   // Open the program and see if it references the expected file.
   base::win::ScopedHandle handle;
   BY_HANDLE_FILE_INFORMATION info = {};
 
   return (OpenForInfo(path, &handle) &&
           GetInfo(handle, &info) &&
           info.dwVolumeSerialNumber == file_info_.dwVolumeSerialNumber &&
           info.nFileIndexHigh == file_info_.nFileIndexHigh &&
           info.nFileIndexLow == file_info_.nFileIndexLow);
 }