Created test for window.history.pushState().

ios/web/navigation/history_state_operations_inttest.mm

Index: ios/web/navigation/history_state_operations_inttest.mm
diff --git a/ios/web/navigation/history_state_operations_inttest.mm b/ios/web/navigation/history_state_operations_inttest.mm
index afd2c86dc0991329f1fbade03b40acf4a56aee24..a305cf3b3a3e3e5c80992120181440eccfc7115d 100644
--- a/ios/web/navigation/history_state_operations_inttest.mm
+++ b/ios/web/navigation/history_state_operations_inttest.mm
@@ -339,3 +339,34 @@ void WaitForNoOpText() {
     return GetJavaScriptState() == new_state;
   });
 }
+
+// Tests that calling window.history.pushState() creates a new NavigationItem
+// and prunes trailing items.
+TEST_F(HistoryStateOperationsTest, PushState) {
+  // Navigate to about:blank then navigate back to the test page.  The created
+  // NavigationItem can be used later to verify that the state is replaced
+  // rather than pushed.
+  GURL about_blank("about:blank");
+  LoadUrl(about_blank);
+  web::NavigationItem* about_blank_item = GetLastCommittedItem();
+  ExecuteBlockAndWaitForLoad(state_operations_url(), ^{

[Eugene But (OOO till 7-30), 2017/01/24 19:26:37]

Not related to this CL, but ExecuteBlockAndWaitForLoad is problematic, because
it does 2 things. Can we implement something like WaitForLoad(GURL) instead?
That method would wait until IsLoading returns true and would check last
committed URL. We use this pattern in EG tests and could use it here.

+    navigation_manager()->GoBack();
+  });
+  ASSERT_EQ(state_operations_url(), GetLastCommittedItem()->GetURL());
+  web::NavigationItem* non_pushed_item = GetLastCommittedItem();
+  // Set up the state parameters and tap the replace state button.
+  std::string empty_state;
+  std::string empty_title;
+  GURL new_url = state_operations_url().Resolve("path");
+  SetStateParams(empty_state, empty_title, new_url);
+  ASSERT_TRUE(web::test::TapWebViewElementWithId(web_state(), kPushStateId));
+  // Verify that the url with the path is pushed.
+  base::test::ios::WaitUntilCondition(^bool {
+    return GetLastCommittedItem()->GetURL() == new_url;
+  });
+  // Verify that a new NavigationItem was created and that the forward item was
+  // pruned.
+  EXPECT_EQ(GetIndexOfNavigationItem(non_pushed_item) + 1,
+            GetIndexOfNavigationItem(GetLastCommittedItem()));
+  EXPECT_EQ(NSNotFound, GetIndexOfNavigationItem(about_blank_item));
+}