[iOS] Remove AppState.window.

AppState's |window| is confusing in multiwindow world. It is equivalent
to AppState.foregroundActiveScene.window. Remove it to avoid confusion.

Bug: none
Change-Id: I3d5c0f10df07050f90380d14133f406ab541d9c2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2193991
Commit-Queue: Stepan Khapugin <stkhapugin@chromium.org>
Auto-Submit: Stepan Khapugin <stkhapugin@chromium.org>
Reviewed-by: Mark Cogan <marq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#771745}

ios/chrome/app/application_delegate/app_state.h

@@ -46,10 +46,6 @@ initWithBrowserLauncher:(id<BrowserLauncher>)browserLauncher
 // application has been woken up by the system for background work.
 @property(nonatomic, readonly) BOOL userInteracted;
 
-// Current foreground active for the application, if any. Some scene's window
-// otherwise. For legacy use cases only, use scene windows instead.
-@property(nonatomic, readonly) UIWindow* window;
-
 // When multiwindow is unavailable, this is the only scene state. It is created
 // by the app delegate.
 @property(nonatomic, strong) SceneState* mainSceneState;

ios/chrome/app/application_delegate/app_state.mm

@@ -183,18 +183,6 @@ initWithBrowserLauncher:(id<BrowserLauncher>)browserLauncher
   _safeModeCoordinator = safeModeCoordinator;
 }
 
-- (UIWindow*)window {
-  return self.foregroundActiveScene ? self.foregroundActiveScene.window
-                                    : self.connectedScenes.firstObject.window;
-}
-
-- (void)setsceneShowingBlockingUI:(SceneState*)sceneState {
-  _sceneShowingBlockingUI = sceneState;
-  for (SceneState* state in self.connectedScenes) {
-    state.presentingModalOverlay = (state != sceneState) && (sceneState != nil);
-  }
-}
-
 #pragma mark - Public methods.
 
 - (void)applicationDidEnterBackground:(UIApplication*)application
@@ -560,14 +548,14 @@ initWithBrowserLauncher:(id<BrowserLauncher>)browserLauncher
 
 - (void)startSafeMode {
   DCHECK(self.foregroundActiveScene);
-  SafeModeCoordinator* safeModeCoordinator =
-      [[SafeModeCoordinator alloc] initWithWindow:self.window];
+  SafeModeCoordinator* safeModeCoordinator = [[SafeModeCoordinator alloc]
+      initWithWindow:self.foregroundActiveScene.window];
 
   self.safeModeCoordinator = safeModeCoordinator;
   [self.safeModeCoordinator setDelegate:self];
 
   // Activate the main window, which will prompt the views to load.
-  [self.window makeKeyAndVisible];
+  [self.foregroundActiveScene.window makeKeyAndVisible];
 
   [self.safeModeCoordinator start];
 }