Mock the LinkDoctor for tests. Should greatly decrease ErrorPage test flakiness.

chrome/browser/tab_contents/tab_contents.cc

Index: chrome/browser/tab_contents/tab_contents.cc
diff --git a/chrome/browser/tab_contents/tab_contents.cc b/chrome/browser/tab_contents/tab_contents.cc
index 1568790eebd51892633df07fbf95a86df798e3c9..e80deda9b9ed8889f9343b294e948421bcceb48c 100644
--- a/chrome/browser/tab_contents/tab_contents.cc
+++ b/chrome/browser/tab_contents/tab_contents.cc
@@ -136,9 +136,6 @@ const float kMaxHeightFactor = 0.6;
 // contents.
 const int kJavascriptMessageExpectedDelay = 1000;
 
-const char kLinkDoctorBaseURL[] =
-    "http://linkhelp.clients.google.com/tbproxy/lh/fixurl";
-
 // The list of prefs we want to observe.
 const wchar_t* kPrefsToObserve[] = {
   prefs::kAlternateErrorPagesEnabled,
@@ -2323,7 +2320,8 @@ GURL TabContents::GetAlternateErrorPageURL() const {
   PrefService* prefs = profile()->GetPrefs();
   DCHECK(prefs);
   if (prefs->GetBoolean(prefs::kAlternateErrorPagesEnabled)) {
-    url = google_util::AppendGoogleLocaleParam(GURL(kLinkDoctorBaseURL));
+    url = google_util::AppendGoogleLocaleParam(
+        GURL(google_util::kLinkDoctorBaseURL));
     url = google_util::AppendGoogleTLDParam(url);
   }
   return url;