Created test verifying resetting the state object after reloading.

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 8c0af0b77cbcaec5afecd7b21f3a904665cf85ef..d6e790bdc46580b257fb360e304530e19b0065cf 100644
--- a/ios/web/navigation/history_state_operations_inttest.mm
+++ b/ios/web/navigation/history_state_operations_inttest.mm
@@ -142,6 +142,15 @@ void LoadUrl(const GURL& url) {
     WaitForPageToLoad();
   }
 
+  // Reloads the page and waits for the load to finish.
+  void Reload() {
+    ExpectPageLoad(current_item()->GetURL());
+    // TODO(crbug.com/677364): Use NavigationManager::Reload() once it no longer
+    // requires a web delegate.
+    web_state()->ExecuteJavaScript(ASCIIToUTF16("window.location.reload()"));
+    WaitForPageToLoad();
+  }
+
   // Set the parameters to use for state operations on the test page.
   void SetStateParams(const std::string& state_object,
                       const std::string& title,
@@ -333,3 +342,33 @@ NSInteger GetIndexOfNavigationItem(const web::NavigationItem* item) {
   EXPECT_EQ(GetIndexOfNavigationItem(current_item()) + 1,
             GetIndexOfNavigationItem(about_blank_item));
 }
+
+// Tests that the state object is reset to the correct value after reloading a
+// page whose state has been replaced.
+TEST_F(HistoryStateOperationsTest, StateReplacementReload) {
+  // 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 17:15:27]

std::string empty_title;

[kkhorimoto, 2017/01/24 05:15:36]

Done.

+  GURL empty_url("");

[Eugene But (OOO till 7-30), 2016/12/29 17:15:27]

GURL empty_url;

[kkhorimoto, 2017/01/24 05:15:36]

Done.

+  SetStateParams(new_state, empty_title, empty_url);
+  ASSERT_TRUE(web::test::TapWebViewElementWithId(web_state(), kReplaceStateID));
+  // Reload the page and check that the state object is present.
+  Reload();
+  ASSERT_TRUE(IsOnLoadTextVisible());
+  __block bool state_object_present = false;
+  base::string16 state_object_script = ASCIIToUTF16("window.history.state");
+  base::test::ios::TimeUntilCondition(
+      ^{
+        web_state()->ExecuteJavaScript(

[Eugene But (OOO till 7-30), 2016/12/29 17:15:27]

Could you please use synchronous API for this.

[kkhorimoto, 2017/01/24 05:15:36]

Done.

+            state_object_script, base::BindBlock(^(const base::Value* result) {
+              std::string state;
+              result->GetAsString(&state);
+              state_object_present = state == new_state;
+            }));
+      },
+      ^bool {
+        return state_object_present;
+      },
+      false, base::TimeDelta::FromSeconds(10.0));
+  EXPECT_TRUE(state_object_present);

[Eugene But (OOO till 7-30), 2016/12/29 17:15:27]

No need for this check.

[kkhorimoto, 2017/01/24 05:15:36]

Done.

+}