Reenable testIncognitoSeparation

Reenables the test. Also fixes the use-after-free of Browser in
SideSwipeController that happens sometimes in tests.

Bug: 1045950
Change-Id: I8e476c0030f890933861e71a62a7e5111abfd60e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2036185
Commit-Queue: Stepan Khapugin <stkhapugin@chromium.org>
Reviewed-by: Mark Cogan <marq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#739438}

ios/chrome/browser/ui/omnibox/popup/omnibox_popup_egtest.mm

@@ -164,8 +164,7 @@ std::unique_ptr<net::test_server::HttpResponse> StandardResponse(
 
 // Tests that the incognito tabs aren't displayed as "opened" tab in the
 // non-incognito suggestions and vice-versa.
-// TODO(crbug.com/1045950): fix and reenable.
-- (void)DISABLED_testIncognitoSeparation {
+- (void)testIncognitoSeparation {
   GURL URL1 = self.testServer->GetURL(kPage1URL);
   GURL URL2 = self.testServer->GetURL(kPage2URL);
   GURL URL3 = self.testServer->GetURL(kPage3URL);

ios/chrome/browser/ui/side_swipe/side_swipe_controller.mm

@@ -11,6 +11,7 @@
 #include "base/scoped_observer.h"
 #import "ios/chrome/browser/browser_state/chrome_browser_state.h"
 #include "ios/chrome/browser/main/browser.h"
+#include "ios/chrome/browser/main/browser_observer.h"
 #import "ios/chrome/browser/snapshots/snapshot_cache.h"
 #import "ios/chrome/browser/snapshots/snapshot_cache_factory.h"
 #import "ios/chrome/browser/snapshots/snapshot_tab_helper.h"
@@ -43,6 +44,8 @@ NSString* const kSideSwipeWillStartNotification =
 NSString* const kSideSwipeDidStopNotification =
     @"kSideSwipeDidStopNotification";
 
+class SideSwipeControllerBrowserRemover;
+
 namespace {
 
 enum class SwipeType { NONE, CHANGE_TAB, CHANGE_PAGE };
@@ -62,8 +65,8 @@ const NSUInteger kIpadGreySwipeTabCount = 8;
                                    WebStateListObserving> {
  @private
 
-  // Browser passed on the initializer.
-  Browser* _browser;
+  // Zeroes out |_browser| when it is destroyed.
+  std::unique_ptr<SideSwipeControllerBrowserRemover> _browserRemover;
 
   // Side swipe view for tab navigation.
   CardSideSwipeView* _tabSideSwipeView;
@@ -107,6 +110,8 @@ const NSUInteger kIpadGreySwipeTabCount = 8;
   std::unique_ptr<AnimatedScopedFullscreenDisabler> _animatedFullscreenDisabler;
 }
 
+// Browser passed on the initializer.
+@property(nonatomic, assign) Browser* browser;
 // Whether to allow navigating from the leading edge.
 @property(nonatomic, assign) BOOL leadingEdgeNavigationEnabled;
 // Whether to allow navigating from the trailing edge.
@@ -140,6 +145,21 @@ const NSUInteger kIpadGreySwipeTabCount = 8;
 - (void)dismissCurtain;
 @end
 
+// A browser observer that nullifies SideSwipeController's pointer to browser
+// when the browser is destroyed.
+class SideSwipeControllerBrowserRemover : public BrowserObserver {
+ public:
+  SideSwipeControllerBrowserRemover(SideSwipeController* controller)
+      : side_swipe_controller_(controller) {}
+
+  void BrowserDestroyed(Browser* browser) override {
+    side_swipe_controller_.browser = nullptr;
+  }
+
+ private:
+  __weak SideSwipeController* side_swipe_controller_;
+};
+
 @implementation SideSwipeController
 
 @synthesize inSwipe = _inSwipe;
@@ -156,6 +176,9 @@ const NSUInteger kIpadGreySwipeTabCount = 8;
   self = [super init];
   if (self) {
     _browser = browser;
+    _browserRemover = std::make_unique<SideSwipeControllerBrowserRemover>(self);
+    _browser->AddObserver(_browserRemover.get());
+
     _webStateListObserver = std::make_unique<WebStateListObserverBridge>(self);
     _browser->GetWebStateList()->AddObserver(_webStateListObserver.get());
     _webStateObserverBridge =
@@ -174,6 +197,11 @@ const NSUInteger kIpadGreySwipeTabCount = 8;
     self.webStateList->RemoveObserver(_webStateListObserver.get());
   }
 
+  if (self.browser) {
+    self.browser->RemoveObserver(_browserRemover.get());
+    self.browser = nullptr;
+  }
+
   _scopedWebStateObserver.reset();
   _webStateObserverBridge.reset();
 }
@@ -203,10 +231,16 @@ const NSUInteger kIpadGreySwipeTabCount = 8;
 }
 
 - (ChromeBrowserState*)browserState {
+  if (!_browser) {
+    return nullptr;
+  }
   return _browser->GetBrowserState();
 }
 
 - (WebStateList*)webStateList {
+  if (!_browser) {
+    return nullptr;
+  }
   return _browser->GetWebStateList();
 }