Fixit: Remove bunch of coverity warnings from chrome/installer/*.

chrome/installer/setup/install.cc

Index: chrome/installer/setup/install.cc
diff --git a/chrome/installer/setup/install.cc b/chrome/installer/setup/install.cc
index 24067d2204c860b506c20396e2ce0ef739a50ca8..c409317c6f4bc01c1937d70302dd963d13f7b260 100644
--- a/chrome/installer/setup/install.cc
+++ b/chrome/installer/setup/install.cc
@@ -33,8 +33,8 @@
 
 namespace {
 
-std::wstring AppendPath(const std::wstring parent_path,
-                        const std::wstring path) {
+std::wstring AppendPath(const std::wstring& parent_path,
+                        const std::wstring& path) {
   std::wstring new_path(parent_path);
   file_util::AppendToPath(&new_path, path);
   return new_path;
@@ -279,7 +279,7 @@ bool Is64bit() {
   return false;
 }
 
-void RegisterChromeOnMachine(std::wstring install_path, int options) {
+void RegisterChromeOnMachine(const std::wstring& install_path, int options) {
   bool system_level = (options & installer_util::SYSTEM_LEVEL) != 0;
   // Try to add Chrome to Media Player shim inclusion list. We don't do any
   // error checking here because this operation will fail if user doesn't