Give SxS distribution its own registration GUIDs.

chrome/installer/util/install_util.cc

Index: chrome/installer/util/install_util.cc
diff --git a/chrome/installer/util/install_util.cc b/chrome/installer/util/install_util.cc
index c8c037df823364a081b3ebac240cb974244d3e27..0bdb454d1dee11e0858e1a9bcfc06b6c3fbc7c39 100644
--- a/chrome/installer/util/install_util.cc
+++ b/chrome/installer/util/install_util.cc
@@ -365,10 +365,27 @@ bool CheckIsChromeSxSProcess() {
   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() {