Simplify update error message support HTML.

Errors from the update mechanism were appearing twice, once
included in the error string generated in google_update_win
and once in OnError() of version_updater_win.  This caused
redundant information like this:

Update failed (error: 1)An error occurred while checking for updates: Update check failed to start (error code 1: 0x80004005).

Now this:

An error occurred while checking for updates: Update check failed to start (error code 1: 0x80004005).

In addition, this allows removal of the check against a specific
error code since that comes with an actual error message already.

The error message has been explicitly stated as being HTML, making
it okay for callers to include mark-up such as links to more info.

For more information, see the discussion on this CL:
https://codereview.chromium.org/1212783003/

BUG=489801

Review URL: https://codereview.chromium.org/1214603005

Cr-Commit-Position: refs/heads/master@{#338282}
diff --git a/chrome/browser/google/google_update_win.h b/chrome/browser/google/google_update_win.h
index 0e02c76..149385a 100644
--- a/chrome/browser/google/google_update_win.h
+++ b/chrome/browser/google/google_update_win.h
@@ -76,11 +76,13 @@
   virtual void OnUpgradeComplete(const base::string16& new_version) = 0;
 
   // Invoked following an unrecoverable error, indicated by |error_code|.
-  // |error_message|, if not empty, contains a localized string that may be
-  // presented to the user explaining the nature of the error. |new_version|, if
-  // not empty, indicates the version to which an upgrade attempt was made.
+  // |html_error_message|, if not empty, must be a localized string containing
+  // all information required by users to act on the error as well as for
+  // support staff to diagnose it (i.e. |error_code| and any other related
+  // state information).  |new_version|, if not empty, indicates the version
+  // to which an upgrade attempt was made.
   virtual void OnError(GoogleUpdateErrorCode error_code,
-                       const base::string16& error_message,
+                       const base::string16& html_error_message,
                        const base::string16& new_version) = 0;
 
  protected: