Fix some case-insensitive cases for StartsWith

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 4fc383ab86bed3bb094798d144231fb5493a1051..e8fd6aa1f4921b467aa284a23438fa0031663e2f 100644
--- a/chrome/installer/util/install_util.cc
+++ b/chrome/installer/util/install_util.cc
@@ -393,7 +393,16 @@ bool InstallUtil::IsPerUserInstall(const base::FilePath& exe_path) {
     env->SetVar(kEnvProgramFilesPath,
                 base::WideToUTF8(program_files_path.value()));
   }
-  return !base::StartsWith(exe_path.value(), program_files_path.value(), false);
+
+  // Return true if the program files path is not a case-insensitive prefix of
+  // the exe path.
+  if (exe_path.value().size() < program_files_path.value().size())
+    return true;
+  DWORD prefix_len = static_cast<DWORD>(program_files_path.value().size());

[grt (UTC plus 2), 2015/07/01 17:55:42]

base::saturated_cast<DWORD, size_t>()?

+  return ::CompareString(LOCALE_USER_DEFAULT, NORM_IGNORECASE,
+                         exe_path.value().data(), prefix_len,
+                         program_files_path.value().data(), prefix_len) !=
+      CSTR_EQUAL;
 }
 
 bool InstallUtil::IsMultiInstall(BrowserDistribution* dist,