[ios] Fix Unwinding of History and ClearBrowsingData when Clear Browsing Data dialog is open

- stops all action sheet coordinators in ClearBrowsingDataTableViewController before dismissing itself.
- sets historyClearBrowsingDataCoordinator to nil after finishing unwinding ClearBrowsingData and History to prevent race condition.

Video: https://drive.google.com/open?id=1wDymlQtfStNWBY9mI9GYqlig8qkipBDF

Bug: 867329
Change-Id: I7c0825b02ed7d3c6122f0a5ae37c99181fc6d182
Reviewed-on: https://chromium-review.googlesource.com/1159683
Commit-Queue: Chris Lu <thegreenfrog@chromium.org>
Reviewed-by: Sergio Collazos <sczs@chromium.org>
Cr-Commit-Position: refs/heads/master@{#580348}

ios/chrome/browser/ui/history/history_clear_browsing_data_coordinator.mm

@@ -24,13 +24,17 @@
 @interface HistoryClearBrowsingDataCoordinator ()<
     UIViewControllerTransitioningDelegate>
 
-// ViewController being managed by this Coordinator.
+// ViewControllers being managed by this Coordinator.
 @property(strong, nonatomic)
     TableViewNavigationController* historyClearBrowsingDataNavigationController;
+@property(strong, nonatomic)
+    ClearBrowsingDataTableViewController* clearBrowsingDataTableViewController;
 
 @end
 
 @implementation HistoryClearBrowsingDataCoordinator
+@synthesize clearBrowsingDataTableViewController =
+    _clearBrowsingDataTableViewController;
 @synthesize dispatcher = _dispatcher;
 @synthesize historyClearBrowsingDataNavigationController =
     _historyClearBrowsingDataNavigationController;
@@ -39,16 +43,17 @@
 @synthesize presentationDelegate = _presentationDelegate;
 
 - (void)start {
-  ClearBrowsingDataTableViewController* clearBrowsingDataTableViewController =
+  self.clearBrowsingDataTableViewController =
       [[ClearBrowsingDataTableViewController alloc]
           initWithBrowserState:self.browserState];
-  clearBrowsingDataTableViewController.extendedLayoutIncludesOpaqueBars = YES;
-  clearBrowsingDataTableViewController.localDispatcher = self;
-  clearBrowsingDataTableViewController.dispatcher = self.dispatcher;
+  self.clearBrowsingDataTableViewController.extendedLayoutIncludesOpaqueBars =
+      YES;
+  self.clearBrowsingDataTableViewController.localDispatcher = self;
+  self.clearBrowsingDataTableViewController.dispatcher = self.dispatcher;
   // Configure and present ClearBrowsingDataNavigationController.
   self.historyClearBrowsingDataNavigationController =
       [[TableViewNavigationController alloc]
-          initWithTable:clearBrowsingDataTableViewController];
+          initWithTable:self.clearBrowsingDataTableViewController];
   self.historyClearBrowsingDataNavigationController.toolbarHidden = YES;
   // Stacks on top of history "bubble" for non-compact devices.
   self.historyClearBrowsingDataNavigationController.transitioningDelegate =
@@ -65,10 +70,7 @@
 
 - (void)stopWithCompletion:(ProceduralBlock)completionHandler {
   if (self.historyClearBrowsingDataNavigationController) {
-    [self.historyClearBrowsingDataNavigationController
-        dismissViewControllerAnimated:YES
-                           completion:completionHandler];
-    self.historyClearBrowsingDataNavigationController = nil;
+    [self dismissClearBrowsingDataWithCompletion:completionHandler];
   } else if (completionHandler) {
     completionHandler();
   }
@@ -93,10 +95,18 @@
 
 - (void)dismissClearBrowsingDataWithCompletion:
     (ProceduralBlock)completionHandler {
+  DCHECK(self.historyClearBrowsingDataNavigationController);
+  [self.clearBrowsingDataTableViewController prepareForDismissal];
   [self.historyClearBrowsingDataNavigationController
       dismissViewControllerAnimated:YES
-                         completion:completionHandler];
-  self.historyClearBrowsingDataNavigationController = nil;
+                         completion:^() {
+                           if (completionHandler) {
+                             completionHandler();
+                           }
+                           self.clearBrowsingDataTableViewController = nil;
+                           self.historyClearBrowsingDataNavigationController =
+                               nil;
+                         }];
 }
 
 #pragma mark - UIViewControllerTransitioningDelegate

ios/chrome/browser/ui/history/history_coordinator.mm

@@ -110,9 +110,11 @@
       self.historyNavigationController = nil;
     };
     if (self.historyClearBrowsingDataCoordinator) {
-      [self.historyClearBrowsingDataCoordinator
-          stopWithCompletion:dismissHistoryNavigation];
+      [self.historyClearBrowsingDataCoordinator stopWithCompletion:^() {
+        dismissHistoryNavigation();
         self.historyClearBrowsingDataCoordinator = nil;
+      }];
+
     } else {
       dismissHistoryNavigation();
     }

ios/chrome/browser/ui/settings/clear_browsing_data_table_view_controller.h

@@ -26,6 +26,10 @@ class ChromeBrowserState;
                                (ChromeTableViewControllerStyle)appBarStyle
     NS_UNAVAILABLE;
 
+// Prepares view controller so that -dismissViewControllerAnimated dismisses it.
+// Call this method before dismissing view controller.
+- (void)prepareForDismissal;
+
 // Local Dispatcher for this ClearBrowsingDataTableView.
 @property(nonatomic, weak) id<ClearBrowsingDataLocalCommands> localDispatcher;
 

ios/chrome/browser/ui/settings/clear_browsing_data_table_view_controller.mm

@@ -115,10 +115,23 @@ class ChromeBrowserState;
 }
 
 - (void)dismiss {
-  [self.alertCoordinator stop];
+  [self prepareForDismissal];
   [self.localDispatcher dismissClearBrowsingDataWithCompletion:nil];
 }
 
+#pragma mark - Public Methods
+
+- (void)prepareForDismissal {
+  if (self.actionSheetCoordinator) {
+    [self.actionSheetCoordinator stop];
+    self.actionSheetCoordinator = nil;
+  }
+  if (self.alertCoordinator) {
+    [self.alertCoordinator stop];
+    self.alertCoordinator = nil;
+  }
+}
+
 #pragma mark - UITableViewDataSource
 
 - (UITableViewCell*)tableView:(UITableView*)tableView