[multiball] Fix multiwindow-disabled app.

Fixes some scene-specific API usage on iOS 13 that's not gated with
multiwindow checks.

Bug: 1133356
Change-Id: I6ead2767526b111d3ad292ac638509428ff3f88f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2437399
Commit-Queue: Stepan Khapugin <stkhapugin@chromium.org>
Reviewed-by: Mark Cogan <marq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#812224}

ios/chrome/app/application_delegate/app_state.mm

@@ -171,13 +171,18 @@ initWithBrowserLauncher:(id<BrowserLauncher>)browserLauncher
     _mainApplicationDelegate = applicationDelegate;
     _appCommandDispatcher = [[CommandDispatcher alloc] init];
 
-    if (@available(iOS 13, *)) {
-      // Subscribe to scene connection notifications.
-      [[NSNotificationCenter defaultCenter]
-          addObserver:self
-             selector:@selector(sceneWillConnect:)
-                 name:UISceneWillConnectNotification
-               object:nil];
+    // Subscribe to scene-related notifications when using scenes.
+    // Note these are also sent when not using scenes, so avoid subscribing to
+    // them unless necessary.
+    if (IsSceneStartupSupported()) {
+      if (@available(iOS 13, *)) {
+        // Subscribe to scene connection notifications.
+        [[NSNotificationCenter defaultCenter]
+            addObserver:self
+               selector:@selector(sceneWillConnect:)
+                   name:UISceneWillConnectNotification
+                 object:nil];
+      }
     }
   }
   return self;
@@ -696,6 +701,7 @@ initWithBrowserLauncher:(id<BrowserLauncher>)browserLauncher
 }
 
 - (void)sceneWillConnect:(NSNotification*)notification {
+  DCHECK(IsSceneStartupSupported());
   if (@available(iOS 13, *)) {
     UIWindowScene* scene =
         base::mac::ObjCCastStrict<UIWindowScene>(notification.object);

ios/chrome/browser/ui/main/incognito_blocker_scene_agent.mm

@@ -76,8 +76,10 @@
 - (void)showOverlay {
   NSArray<UIWindow*>* windows = nil;
 
-  if (@available(iOS 13, *)) {
-    windows = self.sceneState.scene.windows;
+  if (IsMultiwindowSupported()) {
+    if (@available(iOS 13, *)) {
+      windows = self.sceneState.scene.windows;
+    }
   } else {
     windows = UIApplication.sharedApplication.windows;
   }

ios/chrome/browser/ui/main/scene_controller.mm

@@ -308,11 +308,13 @@ const char kMultiWindowOpenInNewWindowHistogram[] =
       level > SceneActivationLevelBackground && !self.hasInitializedUI;
   if (initializingUIInColdStart) {
     [self initializeUI];
-    if (@available(iOS 13, *)) {
-      // Add the scene to the list of connected scene, to restore in case of
-      // crashes.
-      [[PreviousSessionInfo sharedInstance]
-          addSceneSessionID:sceneState.scene.session.persistentIdentifier];
+    if (IsMultiwindowSupported()) {
+      if (@available(iOS 13, *)) {
+        // Add the scene to the list of connected scene, to restore in case of
+        // crashes.
+        [[PreviousSessionInfo sharedInstance]
+            addSceneSessionID:sceneState.scene.session.persistentIdentifier];
+      }
     }
   }
 
@@ -359,9 +361,11 @@ const char kMultiWindowOpenInNewWindowHistogram[] =
   }
 
   if (self.hasInitializedUI && level == SceneActivationLevelUnattached) {
-    if (@available(iOS 13, *)) {
-      [[PreviousSessionInfo sharedInstance]
-          removeSceneSessionID:sceneState.scene.session.persistentIdentifier];
+    if (IsMultiwindowSupported()) {
+      if (@available(iOS 13, *)) {
+        [[PreviousSessionInfo sharedInstance]
+            removeSceneSessionID:sceneState.scene.session.persistentIdentifier];
+      }
     }
     [self teardownUI];
   }
@@ -1585,14 +1589,17 @@ const char kMultiWindowOpenInNewWindowHistogram[] =
 - (BOOL)shouldOpenNTPTabOnActivationOfBrowser:(Browser*)browser {
   // Check if there are pending actions that would result in opening a new tab.
   // In that case, it is not useful to open another tab.
-  if (@available(iOS 13, *)) {
-    for (NSUserActivity* activity in self.sceneState.connectionOptions
-             .userActivities) {
-      if (ActivityIsURLLoad(activity)) {
-        return NO;
+  if (IsSceneStartupSupported()) {
+    if (@available(iOS 13, *)) {
+      for (NSUserActivity* activity in self.sceneState.connectionOptions
+               .userActivities) {
+        if (ActivityIsURLLoad(activity)) {
+          return NO;
+        }
       }
     }
   }
+
   if (self.startupParameters) {
     return NO;
   }

ios/chrome/browser/ui/recent_tabs/BUILD.gn

@@ -154,6 +154,7 @@ source_set("app_support+eg2") {
     "//base/test:test_support",
     "//ios/chrome/browser/browser_state",
     "//ios/chrome/browser/ui/list_model",
+    "//ios/chrome/browser/ui/util:multiwindow_util",
     "//ios/chrome/test/app:test_support",
   ]
 }

ios/chrome/browser/ui/recent_tabs/recent_tabs_app_interface.mm

@@ -5,6 +5,7 @@
 #import "ios/chrome/browser/ui/recent_tabs/recent_tabs_app_interface.h"
 
 #import "ios/chrome/browser/ui/list_model/list_model.h"
+#import "ios/chrome/browser/ui/util/multi_window_support.h"
 #import "ios/chrome/test/app/chrome_test_util.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
@@ -14,15 +15,17 @@
 @implementation RecentTabsAppInterface
 
 + (void)clearCollapsedListViewSectionStates {
-  if (@available(iOS 13, *)) {
-    NSArray<UIWindow*>* windows = [UIApplication sharedApplication].windows;
-    for (UIWindow* window in windows) {
-      UISceneSession* session = window.windowScene.session;
+  if (IsSceneStartupSupported()) {
+    if (@available(iOS 13, *)) {
+      NSArray<UIWindow*>* windows = [UIApplication sharedApplication].windows;
+      for (UIWindow* window in windows) {
+        UISceneSession* session = window.windowScene.session;
 
-      NSMutableDictionary* newUserInfo =
-          [NSMutableDictionary dictionaryWithDictionary:session.userInfo];
-      [newUserInfo removeObjectForKey:kListModelCollapsedKey];
-      session.userInfo = newUserInfo;
+        NSMutableDictionary* newUserInfo =
+            [NSMutableDictionary dictionaryWithDictionary:session.userInfo];
+        [newUserInfo removeObjectForKey:kListModelCollapsedKey];
+        session.userInfo = newUserInfo;
+      }
     }
   } else {
     [NSUserDefaults.standardUserDefaults setObject:@{}