[ios] Clean up uses of private web API.

ios/chrome/browser/tabs/tab.mm

Index: ios/chrome/browser/tabs/tab.mm
diff --git a/ios/chrome/browser/tabs/tab.mm b/ios/chrome/browser/tabs/tab.mm
index a4145134f03b4ea654cd602d2d42032d7d0884e5..3b94a7e5f17d072ce6a37b4b3b194c18548b963c 100644
--- a/ios/chrome/browser/tabs/tab.mm
+++ b/ios/chrome/browser/tabs/tab.mm
@@ -1022,12 +1022,6 @@ void TabInfoBarObserver::OnInfoBarReplaced(infobars::InfoBar* old_infobar,
   }
 }
 
-// Stop the page loading.
-// Equivalent to the user pressing 'stop', or a window.stop() command.
-- (void)stopLoading {
-  [self.webController stopLoading];
-}
-
 // Halt the tab, which amounts to halting its webController.
 - (void)terminateNetworkActivity {
   [self.webController terminateNetworkActivity];
@@ -1760,10 +1754,6 @@ void TabInfoBarObserver::OnInfoBarReplaced(infobars::InfoBar* old_infobar,
   [overscrollActionsController_ clear];
 }
 
-- (void)setWebUsageEnabled:(BOOL)webUsageEnabled {
-  [self.webController setWebUsageEnabled:webUsageEnabled];
-}
-
 - (void)webStateDidSuppressDialog:(web::WebState*)webState {
   DCHECK(isPrerenderTab_);
   [delegate_ discardPrerender];