Fix safe mode exit crash

Scene UI is not initialized in safe mode.
When exiting safe mode, initialize the UI of the sceneState
before continuing the startup sequence.

Bug: 1137310
Change-Id: I61c4a3faeed8d7728a8ecbb1b191e8621e72e4f2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2476280
Commit-Queue: Olivier Robin <olivierrobin@chromium.org>
Reviewed-by: Stepan Khapugin <stkhapugin@chromium.org>
Reviewed-by: Mark Cogan <marq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#818898}

ios/chrome/app/application_delegate/app_state.h

@@ -32,9 +32,9 @@ class ChromeBrowserState;
 // On iOS 12, called when the mainSceneState is set.
 - (void)appState:(AppState*)appState sceneConnected:(SceneState*)sceneState;
 
-// Called when the first scene becomes active.
+// Called when the first scene initializes its UI.
 - (void)appState:(AppState*)appState
-    firstSceneActivated:(SceneState*)sceneState;
+    firstSceneHasInitializedUI:(SceneState*)sceneState;
 
 // Called after the app exits safe mode.
 - (void)appStateDidExitSafeMode:(AppState*)appState;

ios/chrome/app/application_delegate/app_state.mm

@@ -139,6 +139,9 @@ NSString* const kStartupAttemptReset = @"StartupAttempReset";
 // never reset.
 @property(nonatomic, assign) BOOL firstSceneHasActivated;
 
+// This flag is set when the first scene has initialized its UI and never reset.
+@property(nonatomic, assign) BOOL firstSceneHasInitializedUI;
+
 // The current blocker target if any.
 @property(nonatomic, weak, readwrite) id<UIBlockerTarget> uiBlockerTarget;
 
@@ -698,14 +701,21 @@ initWithBrowserLauncher:(id<BrowserLauncher>)browserLauncher
   return self.uiBlockerTarget;
 }
 
+#pragma mark - SceneStateObserver
+
+- (void)sceneStateHasInitializedUI:(SceneState*)sceneState {
+  if (self.firstSceneHasInitializedUI) {
+    return;
+  }
+  self.firstSceneHasInitializedUI = YES;
+  [self.observers appState:self firstSceneHasInitializedUI:sceneState];
+}
+
 - (void)sceneState:(SceneState*)sceneState
     transitionedToActivationLevel:(SceneActivationLevel)level {
   if (level >= SceneActivationLevelForegroundActive) {
     if (!self.firstSceneHasActivated) {
       self.firstSceneHasActivated = YES;
-
-      [self.observers appState:self firstSceneActivated:sceneState];
-
       if (self.isInSafeMode) {
         // Safe mode can only be started when there's a window, so the actual
         // safe mode has been postponed until now.

ios/chrome/app/main_controller.mm

@@ -603,14 +603,8 @@ void MainControllerAuthenticationServiceDelegate::ClearBrowsingData(
 
 // Called when the first scene becomes active.
 - (void)appState:(AppState*)appState
-    firstSceneActivated:(SceneState*)sceneState {
-  if (appState.isInSafeMode) {
-    return;
-  }
-  [self startUpAfterFirstWindowCreated];
-}
-
-- (void)appStateDidExitSafeMode:(AppState*)appState {
+    firstSceneHasInitializedUI:(SceneState*)sceneState {
+  DCHECK(!appState.isInSafeMode);
   [self startUpAfterFirstWindowCreated];
 }
 

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

@@ -153,9 +153,6 @@ const char kMultiWindowOpenInNewWindowHistogram[] =
 // browser state level UrlLoadingService instances.
 @property(nonatomic, assign) SceneUrlLoadingService* sceneURLLoadingService;
 
-// A flag that keeps track of the UI initialization for the controlled scene.
-@property(nonatomic, assign) BOOL hasInitializedUI;
-
 // Returns YES if the settings are presented, either from
 // self.settingsNavigationController or from SigninCoordinator.
 @property(nonatomic, assign, readonly, getter=isSettingsViewPresented)
@@ -306,8 +303,8 @@ const char kMultiWindowOpenInNewWindowHistogram[] =
     // ends.
     return;
   }
-  BOOL initializingUIInColdStart =
-      level > SceneActivationLevelBackground && !self.hasInitializedUI;
+  BOOL initializingUIInColdStart = level > SceneActivationLevelBackground &&
+                                   !self.sceneState.hasInitializedUI;
   if (initializingUIInColdStart) {
     [self initializeUI];
     if (IsMultiwindowSupported()) {
@@ -362,7 +359,8 @@ const char kMultiWindowOpenInNewWindowHistogram[] =
     }
   }
 
-  if (self.hasInitializedUI && level == SceneActivationLevelUnattached) {
+  if (self.sceneState.hasInitializedUI &&
+      level == SceneActivationLevelUnattached) {
     if (IsMultiwindowSupported()) {
       if (@available(iOS 13, *)) {
         if (IsMultipleScenesSupported()) {
@@ -551,12 +549,12 @@ const char kMultiWindowOpenInNewWindowHistogram[] =
 #pragma mark - private
 
 - (void)initializeUI {
-  if (self.hasInitializedUI) {
+  if (self.sceneState.hasInitializedUI) {
     return;
   }
 
   [self startUpChromeUI];
-  self.hasInitializedUI = YES;
+  self.sceneState.hasInitializedUI = YES;
 }
 
 // Returns YES if restore prompt can be shown.
@@ -745,7 +743,7 @@ const char kMultiWindowOpenInNewWindowHistogram[] =
 // This method completely destroys all of the UI. It should be called when the
 // scene is disconnected.
 - (void)teardownUI {
-  if (!self.hasInitializedUI) {
+  if (!self.sceneState.hasInitializedUI) {
     return;  // Nothing to do.
   }
 
@@ -776,7 +774,7 @@ const char kMultiWindowOpenInNewWindowHistogram[] =
   [self.browserViewWrangler shutdown];
   self.browserViewWrangler = nil;
 
-  self.hasInitializedUI = NO;
+  self.sceneState.hasInitializedUI = NO;
 
   [self.sceneState.appState removeObserver:self];
 }

ios/chrome/browser/ui/main/scene_state.h

@@ -100,6 +100,9 @@ typedef NS_ENUM(NSUInteger, SceneActivationLevel) {
 // |UISceneDelegate scene:continueUserActivity:| and needs to be opened.
 @property(nonatomic) NSUserActivity* pendingUserActivity;
 
+// A flag that keeps track of the UI initialization for the controlled scene.
+@property(nonatomic, assign) BOOL hasInitializedUI;
+
 // Adds an observer to this scene state. The observers will be notified about
 // scene state changes per SceneStateObserver protocol.
 - (void)addObserver:(id<SceneStateObserver>)observer;

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

@@ -113,6 +113,16 @@
   [self.observers sceneState:self transitionedToActivationLevel:newLevel];
 }
 
+- (void)setHasInitializedUI:(BOOL)hasInitializedUI {
+  if (_hasInitializedUI == hasInitializedUI) {
+    return;
+  }
+  _hasInitializedUI = hasInitializedUI;
+  if (hasInitializedUI) {
+    [self.observers sceneStateHasInitializedUI:self];
+  }
+}
+
 - (id<BrowserInterfaceProvider>)interfaceProvider {
   return self.controller.interfaceProvider;
 }

ios/chrome/browser/ui/main/scene_state_observer.h

@@ -26,6 +26,8 @@ enum SceneActivationLevel : NSUInteger;
 - (void)sceneStateWillHideModalOverlay:(SceneState*)sceneState;
 // Notifies when presentingModalOverlay has been set to false.
 - (void)sceneStateDidHideModalOverlay:(SceneState*)sceneState;
+// Notifies when hasInitializedUI has been set.
+- (void)sceneStateHasInitializedUI:(SceneState*)sceneState;
 // Notifies when URLContexts have been added to |URLContextsToOpen|.
 - (void)sceneState:(SceneState*)sceneState
     hasPendingURLs:(NSSet<UIOpenURLContext*>*)URLContexts