Installer string cleaning following Chrome Frame removal.

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 fa258abc65eaeacbad63109ace978903c3c116fa..94c0a2b31f4bfac93d215c86494426122f8396b9 100644
--- a/chrome/installer/setup/setup_main.cc
+++ b/chrome/installer/setup/setup_main.cc
@@ -581,10 +581,8 @@ bool CheckPreInstallConditions(const InstallationState& original_state,
             base::LaunchProcess(cmd, base::LaunchOptions(), NULL);
           }
         } else {
-          // Display an error message for other products.
-          *status = installer::SYSTEM_LEVEL_INSTALL_EXISTS;
-          installer_state->WriteInstallerResult(
-              *status, IDS_INSTALL_SYSTEM_LEVEL_EXISTS_BASE, NULL);
+          // It's not possible to install anything other than Chrome.
+          NOTREACHED();

[gab, 2014/01/09 21:59:15]

It is possible that an old multi-install system-level CF remains on the system
though?

Wouldn't installing a user-level Chrome in that case trip this?

[grt (UTC plus 2), 2014/01/10 12:10:52]

No. They would have already been removed by now by
UninstallMultiChromeFrameIfPresent in setup_main.
I don't think so, but please double-check my logic. Thanks.

[gab, 2014/01/10 16:28:03]

Well if you install user-level Chrome, it means you're likely not running
elevated, and thus you can't run UninstallMultiChromeFrameIfPresent() for a
system-level multi-CF, right? You could try to elevate (don't think we do that
currently?), but that could also fail.

So this code path would hit if a multi-CF is still present and you try to
install user-level Chrome, right?

In fact, isn't this a bigger problem for which we don't have a current solution
for?

[gab, 2014/01/10 20:41:39]

Ah ok, just realized this was doing the check whether the product being
installed is also found at system-level (not whether any other product is found
at system-level).

So indeed existing CF installs don't matter. What matters is that we are no
longer installing CF.

How about changing the comment to:

// It's no longer possible for the product being installed to be anything other
than Chrome.

?

Other than that, lgtm!

[grt (UTC plus 2), 2014/01/10 21:42:27]

Done.

Thanks for putting a lot of thought into this. I appreciate the scrutiny!

         }
         return false;
       }