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..5e17561ae5e7eb800c0eaf6fc5e19e7ee9d9a532 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];
 }
 
+- (BOOL)tabHelperShouldBeActive:(NSString*)tabHelperID {

[Eugene But (OOO till 7-30), 2017/04/10 22:56:28]

nit: Do you want to pragma mark this?

[PL, 2017/04/11 01:35:21]

Done, thanks!

+  BOOL shouldBeActive = YES;
+  if (tabHelperID == SadTabTabHelperID) {
+    UIApplicationState state = UIApplication.sharedApplication.applicationState;
+    BOOL applicationIsActive = IsApplicationStateNotActive(state) == NO;

[Eugene But (OOO till 7-30), 2017/04/10 22:56:28]

Comparing BOOL variable to NO may not always work as expected on 32-bit
platform:
https://google.github.io/styleguide/objcguide.xml#BOOL_Pitfalls

[PL, 2017/04/11 01:35:21]

Done: Tweaked as discussed, thanks!

+    shouldBeActive = (visible_ && applicationIsActive);
+  }
+  return shouldBeActive;
+}
+
 @end
 
 #pragma mark - TestingSupport