Allow chrome to become the os default handler for arbitrary protocols on mac/win.

chrome/installer/setup/setup_main.cc

Index: chrome/installer/setup/setup_main.cc
diff --git a/chrome/installer/setup/setup_main.cc b/chrome/installer/setup/setup_main.cc
index 15e08477d8f16faf9119d7e38c665825deb21ef1..5563a23ae0a6b29a58ca67ebcba79f957e53d5bb 100644
--- a/chrome/installer/setup/setup_main.cc
+++ b/chrome/installer/setup/setup_main.cc
@@ -848,8 +848,17 @@ bool HandleNonInstallCmdLineOptions(const InstallationState& original_state,
         suffix = cmd_line.GetSwitchValueNative(
             installer::switches::kRegisterChromeBrowserSuffix);
       }
-      *exit_code = ShellUtil::RegisterChromeBrowser(
-          chrome_install->distribution(), chrome_exe, suffix, false);
+      if (cmd_line.HasSwitch(
+          installer::switches::kRegisterURLProtocol)) {
+        std::wstring protocol = cmd_line.GetSwitchValueNative(
+            installer::switches::kRegisterURLProtocol);
+        *exit_code = ShellUtil::RegisterChromeForProtocol(
+            chrome_install->distribution(), chrome_exe, suffix, protocol,
+            false);
+      } else {
+        *exit_code = ShellUtil::RegisterChromeBrowser(
+            chrome_install->distribution(), chrome_exe, suffix, false);
+      }
     } else {
       LOG(DFATAL) << "Can't register browser - Chrome distribution not found";
       *exit_code = installer::UNKNOWN_STATUS;