[ios] Change API to inform WebStateList of opener-opened relationship.

ios/shared/chrome/browser/tabs/web_state_opener_unittest.mm

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#import "ios/shared/chrome/browser/tabs/web_state_opener.h"
+
+#include <memory>
+
+#include "base/memory/ptr_util.h"
+#import "ios/web/public/test/fakes/test_navigation_manager.h"
+#import "ios/web/public/test/fakes/test_web_state.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "testing/platform_test.h"
+
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
+namespace {
+
+class FakeNavigationManager : public web::TestNavigationManager {
+ public:
+  explicit FakeNavigationManager(int last_committed_item_index)
+      : last_committed_item_index_(last_committed_item_index) {}
+
+  // web::NavigationManager implementation.
+  int GetLastCommittedItemIndex() const override {
+    return last_committed_item_index_;
+  }
+
+ private:
+  int last_committed_item_index_;
+
+  DISALLOW_COPY_AND_ASSIGN(FakeNavigationManager);
+};
+
+}  // namespace
+
+class WebStateOpenerTest : public PlatformTest {
+ public:
+  WebStateOpenerTest() = default;
+
+  std::unique_ptr<web::WebState> CreateWebState(int last_committed_item_index) {
+    auto test_web_state = base::MakeUnique<web::TestWebState>();
+    test_web_state->SetNavigationManager(
+        base::MakeUnique<FakeNavigationManager>(last_committed_item_index));
+    // TODO(crbug.com/703565): remove std::move() once Xcode 9.0+ is required.
+    return std::move(test_web_state);
+  }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(WebStateOpenerTest);
+};
+
+TEST_F(WebStateOpenerTest, NullWebState) {
+  WebStateOpener opener(nullptr);
+
+  EXPECT_EQ(nullptr, opener.opener);
+  EXPECT_EQ(-1, opener.navigation_index);
+}
+
+TEST_F(WebStateOpenerTest, DefaultNavigationIndex) {
+  std::unique_ptr<web::WebState> web_state = CreateWebState(2);
+  WebStateOpener opener(web_state.get());
+
+  EXPECT_EQ(web_state.get(), opener.opener);
+  EXPECT_EQ(2, opener.navigation_index);
+}
+
+TEST_F(WebStateOpenerTest, ExplicitNavigationIndex) {
+  std::unique_ptr<web::WebState> web_state = CreateWebState(2);
+  WebStateOpener opener(web_state.get(), 1);
+
+  EXPECT_EQ(web_state.get(), opener.opener);
+  EXPECT_EQ(1, opener.navigation_index);
+}