Created test verifying setting the state object via replaceState()

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 52cc4f2a149fd0cced972562b09fc14a0ba1fe08..8c0af0b77cbcaec5afecd7b21f3a904665cf85ef 100644
--- a/ios/web/navigation/history_state_operations_inttest.mm
+++ b/ios/web/navigation/history_state_operations_inttest.mm
@@ -5,8 +5,10 @@
 #import "base/mac/bind_objc_block.h"
 #include "base/memory/ptr_util.h"
 #include "base/strings/stringprintf.h"
+#import "base/strings/sys_string_conversions.h"

[Eugene But (OOO till 7-30), 2016/12/29 17:12:59]

s/import/include

[kkhorimoto, 2017/01/24 04:57:15]

Done.

 #include "base/strings/utf_string_conversions.h"
 #include "base/test/ios/wait_util.h"
+#import "ios/web/navigation/navigation_item_impl.h"
 #include "ios/web/public/navigation_item.h"
 #include "ios/web/public/navigation_manager.h"
 #import "ios/web/public/test/http_server.h"
@@ -295,3 +297,39 @@ NSInteger GetIndexOfNavigationItem(const web::NavigationItem* item) {
   EXPECT_EQ(GetIndexOfNavigationItem(current_item()) + 1,
             GetIndexOfNavigationItem(about_blank_item));
 }
+
+// Tests that calling window.history.replaceState() with a new state object
+// replaces the state object for the current NavigationItem.
+TEST_F(HistoryStateOperationsTest, StateReplacement) {
+  // 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 = current_item();
+  ExpectPageLoad(state_operations_url());
+  navigation_manager()->GoBack();
+  WaitForPageToLoad();
+  ASSERT_EQ(state_operations_url(), current_item()->GetURL());
+  // Set up the state parameters and tap the replace state button.
+  std::string new_state("STATE OBJECT");
+  std::string empty_title("");

[Eugene But (OOO till 7-30), 2016/12/29 17:12:59]

std::string empty_title;

[kkhorimoto, 2017/01/24 04:57:15]

Done.

+  GURL empty_url("");

[Eugene But (OOO till 7-30), 2016/12/29 17:12:59]

GURL empty_url;

[kkhorimoto, 2017/01/24 04:57:15]

Done.

+  SetStateParams(new_state, empty_title, empty_url);
+  ASSERT_TRUE(web::test::TapWebViewElementWithId(web_state(), kReplaceStateID));
+  // Verify that the state is reflected in the latest NavigationItem.
+  std::string serialized_state("\"STATE OBJECT\"");
+  __block bool state_updated = false;
+  base::test::ios::WaitUntilCondition(^bool {
+    web::NavigationItemImpl* item =
+        static_cast<web::NavigationItemImpl*>(current_item());
+    std::string item_state =
+        base::SysNSStringToUTF8(item->GetSerializedStateObject());

[Eugene But (OOO till 7-30), 2016/12/29 17:12:59]

Is there a way to avoid using implementation details?

[kkhorimoto, 2017/01/24 04:57:15]

Not really.  NavigationEntry doesn't expose the state object, so it's better for
us to also keep it contained to the implementation file.  I've also added a
check for the actual state object returned by JavaScript, but it'd be better to
check the NavigationItem state as well.

+    state_updated = item_state == serialized_state;

[Eugene But (OOO till 7-30), 2016/12/29 17:13:00]

return item_state == serialized_state;

[kkhorimoto, 2017/01/24 04:57:15]

Done.

+    return state_updated;
+  });
+  EXPECT_TRUE(state_updated);

[Eugene But (OOO till 7-30), 2016/12/29 17:13:00]

There is no need for this check.

[kkhorimoto, 2017/01/24 04:57:15]

Done.

+  // Verify that the forward navigation was not pruned.
+  EXPECT_EQ(GetIndexOfNavigationItem(current_item()) + 1,
+            GetIndexOfNavigationItem(about_blank_item));
+}