Refactor creation of SadTabView into a tab helper object

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 f07a8a1f78f62fab739fa8b413f5b13e08fa584d..8835dc67d4d750eca62c0ed9fd90d3aed33620a9 100644
--- a/ios/chrome/browser/tabs/tab.mm
+++ b/ios/chrome/browser/tabs/tab.mm
@@ -101,7 +101,6 @@
 #import "ios/chrome/browser/ui/prerender_delegate.h"
 #import "ios/chrome/browser/ui/reader_mode/reader_mode_checker.h"
 #import "ios/chrome/browser/ui/reader_mode/reader_mode_controller.h"
-#import "ios/chrome/browser/ui/sad_tab/sad_tab_view.h"
 #include "ios/chrome/browser/ui/ui_util.h"
 #import "ios/chrome/browser/web/auto_reload_bridge.h"
 #import "ios/chrome/browser/web/external_app_launcher.h"
@@ -1945,19 +1944,6 @@ void TabInfoBarObserver::OnInfoBarReplaced(infobars::InfoBar* old_infobar,
 
   if (visible_) {
     if (!applicationIsNotActive) {
-      base::WeakNSObject<Tab> weakSelf(self);
-      base::scoped_nsobject<SadTabView> sadTabView(
-          [[SadTabView alloc] initWithReloadHandler:^{
-            base::scoped_nsobject<Tab> strongSelf([weakSelf retain]);
-
-            // |check_for_repost| is true because this is called from SadTab and
-            // explicitly initiated by the user.
-            [strongSelf navigationManager]->Reload(web::ReloadType::NORMAL,
-                                                   true /* check_for_repost */);
-          }]);
-      base::scoped_nsobject<CRWContentView> contentView(
-          [[CRWGenericContentView alloc] initWithView:sadTabView]);
-      self.webState->ShowTransientContentView(contentView);
       [fullScreenController_ disableFullScreen];
     }
   } else {
@@ -2088,6 +2074,16 @@ void TabInfoBarObserver::OnInfoBarReplaced(infobars::InfoBar* old_infobar,
   [inputAccessoryViewController_ wasHidden];
 }
 
+#pragma mark - SadTabTabHelperDelegate
+
+- (BOOL)isTabVisibleForTabHelper:(SadTabTabHelper*)tabHelper {
+  BOOL shouldBeActive = YES;

[Eugene But (OOO till 7-30), 2017/04/11 15:17:00]

How about this?:

UIApplicationState state = UIApplication.sharedApplication.applicationState;
return visible_ && !IsApplicationStateNotActive(state);

[kkhorimoto, 2017/04/11 17:38:02]

+1, or at least rename |shouldBeActive| to |isTabVisible|

[peterlaurens, 2017/04/11 21:57:26]

Done, thanks! 

To explain why I wrote this like this:
• I wanted to make this as readable as possible and avoid a double-negative
• I have preferred to use local variables that are set and then returned, as 
I've found that can help logging or making quick changes to force a state
during debugging.

I understand that this is less applicable here though, so happy to make this
change!

+  UIApplicationState state = UIApplication.sharedApplication.applicationState;
+  bool applicationIsActive = !IsApplicationStateNotActive(state);
+  shouldBeActive = (visible_ && applicationIsActive);
+  return shouldBeActive;
+}
+
 @end
 
 #pragma mark - TestingSupport