Another clean up fpr HTTP auth committed interstitials feature

The flag and base::Feature instance was removed, but still
flag description strings and base::Feature declaration are
remained.

This patch removes them.

Bug: 963307
Change-Id: Ic38e5dffabbb4967ee95e229d99ffd77d5950509
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2063618
Auto-Submit: Takashi Toyoshima <toyoshim@chromium.org>
Reviewed-by: Emily Stark <estark@chromium.org>
Commit-Queue: Takashi Toyoshima <toyoshim@chromium.org>
Cr-Commit-Position: refs/heads/master@{#742979}

chrome/browser/flag_descriptions.cc

@@ -1071,12 +1071,6 @@ const char kHostedAppShimCreationName[] =
 const char kHostedAppShimCreationDescription[] =
     "Create app shims on Mac when creating a hosted app.";
 
-const char kHTTPAuthCommittedInterstitialsName[] =
-    "Enable Committed Interstitials for HTTP Auth";
-const char kHTTPAuthCommittedInterstitialsDescription[] =
-    "Use committed error pages instead of transient navigation entries "
-    "for HTTP auth interstitial pages.";
-
 const char kIgnoreGpuBlacklistName[] = "Override software rendering list";
 const char kIgnoreGpuBlacklistDescription[] =
     "Overrides the built-in software rendering list and enables "

chrome/browser/flag_descriptions.h

@@ -632,9 +632,6 @@ extern const char kHostedAppQuitNotificationDescription[];
 extern const char kHostedAppShimCreationName[];
 extern const char kHostedAppShimCreationDescription[];
 
-extern const char kHTTPAuthCommittedInterstitialsName[];
-extern const char kHTTPAuthCommittedInterstitialsDescription[];
-
 extern const char kIgnoreGpuBlacklistName[];
 extern const char kIgnoreGpuBlacklistDescription[];
 

chrome/common/chrome_features.h

@@ -264,9 +264,6 @@ COMPONENT_EXPORT(CHROME_FEATURES)
 extern const base::Feature kHappinessTrackingSurveysForDesktopSettingsPrivacy;
 #endif
 
-COMPONENT_EXPORT(CHROME_FEATURES)
-extern const base::Feature kHTTPAuthCommittedInterstitials;
-
 #if defined(OS_WIN)
 // Only has an effect in branded builds.
 COMPONENT_EXPORT(CHROME_FEATURES)