[iOS] Close NTP when switching tab

When the user switch from a NTP which doesn't have a back/forward
history to an open tab, the tab should be closed.

Bug: 908010, 908409
Change-Id: Ie4c783bef4c43ddafa175ba5796bd2a0b05cc54c
Reviewed-on: https://chromium-review.googlesource.com/c/1349264
Commit-Queue: Gauthier Ambard <gambard@chromium.org>
Reviewed-by: Stepan Khapugin <stkhapugin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#611123}

ios/chrome/browser/ui/browser_view_controller.mm

@@ -4611,6 +4611,7 @@ applicationCommandEndpoint:(id<ApplicationCommands>)applicationCommandEndpoint
 - (void)switchToTabWithURL:(const GURL&)URL {
   NSInteger newWebStateIndex = 0;
   WebStateList* webStateList = self.tabModel.webStateList;
+  NSInteger currentWebStateIndex = webStateList->active_index();
   web::WebState* currentWebState = webStateList->GetActiveWebState();
 
   // TODO(crbug.com/893121): This should probably live in the WebStateList.
@@ -4667,6 +4668,16 @@ applicationCommandEndpoint:(id<ApplicationCommands>)applicationCommandEndpoint
                              inPosition:position];
 
   webStateList->ActivateWebStateAt(newWebStateIndex);
+
+  // Close the tab if it is NTP with no back/forward history to avoid having
+  // empty tabs.
+  if (IsVisibleURLNewTabPage(currentWebState) &&
+      currentWebState->GetNavigationManager() &&
+      !currentWebState->GetNavigationManager()->CanGoBack() &&
+      !currentWebState->GetNavigationManager()->CanGoForward()) {
+    webStateList->CloseWebStateAt(currentWebStateIndex,
+                                  WebStateList::CLOSE_USER_ACTION);
+  }
 }
 
 #pragma mark - TabModelObserver methods

ios/chrome/browser/ui/omnibox/popup/BUILD.gn

@@ -96,6 +96,7 @@ source_set("eg_tests") {
     "//base/test:test_support",
     "//components/omnibox/browser",
     "//ios/chrome/browser/ui:feature_flags",
+    "//ios/chrome/browser/ui/content_suggestions:content_suggestions_constant",
     "//ios/chrome/browser/ui/tab_grid:egtest_support",
     "//ios/chrome/test/earl_grey:test_support",
     "//ios/testing/earl_grey:earl_grey_support",

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

@@ -8,6 +8,7 @@
 #include "base/strings/sys_string_conversions.h"
 #include "base/test/scoped_feature_list.h"
 #include "components/omnibox/browser/omnibox_field_trial.h"
+#import "ios/chrome/browser/ui/content_suggestions/ntp_home_constant.h"
 #import "ios/chrome/browser/ui/omnibox/popup/omnibox_popup_row.h"
 #import "ios/chrome/browser/ui/tab_grid/tab_grid_egtest_util.h"
 #import "ios/chrome/test/earl_grey/chrome_earl_grey.h"
@@ -242,4 +243,57 @@ std::unique_ptr<net::test_server::HttpResponse> StandardResponse(
                      nil)] assertWithMatcher:grey_nil()];
 }
 
+- (void)testCloseNTPWhenSwitching {
+  // Open the first page.
+  GURL URL1 = self.testServer->GetURL(kPage1URL);
+  [ChromeEarlGrey loadURL:URL1];
+  [ChromeEarlGrey waitForWebViewContainingText:kPage1];
+
+  // Open a new tab and switch to the first tab.
+  [ChromeEarlGrey openNewTab];
+  [[EarlGrey
+      selectElementWithMatcher:grey_accessibilityID(
+                                   ntp_home::FakeOmniboxAccessibilityID())]
+      performAction:grey_typeText(base::SysUTF8ToNSString(URL1.host()))];
+  [[EarlGrey
+      selectElementWithMatcher:
+          grey_allOf(grey_ancestor(PopupRowWithUrl(URL1)),
+                     grey_accessibilityID(
+                         kOmniboxPopupRowSwitchTabAccessibilityIdentifier),
+                     nil)] performAction:grey_tap()];
+  [ChromeEarlGrey waitForWebViewContainingText:kPage1];
+
+  // Check that the other tab is closed.
+  [ChromeEarlGrey waitForMainTabCount:1];
+}
+
+- (void)testDontCloseNTPWhenSwitchingWithForwardHistory {
+  // Open the first page.
+  GURL URL1 = self.testServer->GetURL(kPage1URL);
+  [ChromeEarlGrey loadURL:URL1];
+  [ChromeEarlGrey waitForWebViewContainingText:kPage1];
+
+  // Open a new tab, navigate to a page and go back to have forward history.
+  [ChromeEarlGrey openNewTab];
+  [ChromeEarlGrey loadURL:URL1];
+  [ChromeEarlGrey waitForWebViewContainingText:kPage1];
+  [ChromeEarlGrey goBack];
+
+  // Navigate to the other tab.
+  [[EarlGrey
+      selectElementWithMatcher:grey_accessibilityID(
+                                   ntp_home::FakeOmniboxAccessibilityID())]
+      performAction:grey_typeText(base::SysUTF8ToNSString(URL1.host()))];
+  [[EarlGrey
+      selectElementWithMatcher:
+          grey_allOf(grey_ancestor(PopupRowWithUrl(URL1)),
+                     grey_accessibilityID(
+                         kOmniboxPopupRowSwitchTabAccessibilityIdentifier),
+                     nil)] performAction:grey_tap()];
+  [ChromeEarlGrey waitForWebViewContainingText:kPage1];
+
+  // Check that the other tab is not closed.
+  [ChromeEarlGrey waitForMainTabCount:2];
+}
+
 @end