Do not allow GuestViewManager to (re)use an instance ID that was already removed.

chrome/browser/guest_view/guest_view_manager_unittest.cc

+// Copyright 2014 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.
+
+#include "chrome/browser/guest_view/guest_view_manager.h"
+
+#include "chrome/test/base/testing_profile.h"
+#include "content/public/test/test_browser_thread_bundle.h"
+#include "content/public/test/web_contents_tester.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+using content::WebContents;
+using content::WebContentsTester;
+
+class GuestViewManagerTest : public testing::Test {
+ public:
+  GuestViewManagerTest() {}
+  virtual ~GuestViewManagerTest() {}
+
+  scoped_ptr<WebContents> CreateWebContents() {
+    return scoped_ptr<WebContents>(
+        WebContentsTester::CreateTestWebContents(&profile_, NULL));
+  }
+
+ private:
+  content::TestBrowserThreadBundle thread_bundle_;
+  TestingProfile profile_;
+
+  DISALLOW_COPY_AND_ASSIGN(GuestViewManagerTest);
+};
+
+// This class allows us to access some private variables in
+// GuestViewManager.
+class TestGuestViewManager : public GuestViewManager {
+ public:
+  explicit TestGuestViewManager(content::BrowserContext* context)
+      : GuestViewManager(context) {}
+
+  int last_instance_id_removed_for_testing() {
+    return last_instance_id_removed_;
+  }
+
+  size_t GetRemovedInstanceIdSize() { return removed_instance_ids_.size(); }
+
+ private:
+  using GuestViewManager::last_instance_id_removed_;
+  using GuestViewManager::removed_instance_ids_;
+
+  DISALLOW_COPY_AND_ASSIGN(TestGuestViewManager);
+};
+
+TEST_F(GuestViewManagerTest, AddRemove) {
+  TestingProfile profile;
+  scoped_ptr<TestGuestViewManager> manager(new TestGuestViewManager(&profile));
+
+  scoped_ptr<WebContents> web_contents1(CreateWebContents());
+  scoped_ptr<WebContents> web_contents2(CreateWebContents());
+  scoped_ptr<WebContents> web_contents3(CreateWebContents());
+
+  EXPECT_EQ(0, manager->last_instance_id_removed_for_testing());
+
+  EXPECT_TRUE(manager->CanUseGuestInstanceID(1));
+  EXPECT_TRUE(manager->CanUseGuestInstanceID(2));
+  EXPECT_TRUE(manager->CanUseGuestInstanceID(3));
+
+  manager->AddGuest(1, web_contents1.get());
+  manager->AddGuest(2, web_contents2.get());
+  manager->RemoveGuest(2);
+
+  // Since we removed 2, it would be an invalid ID.
+  EXPECT_TRUE(manager->CanUseGuestInstanceID(1));
+  EXPECT_FALSE(manager->CanUseGuestInstanceID(2));
+  EXPECT_TRUE(manager->CanUseGuestInstanceID(3));
+
+  EXPECT_EQ(0, manager->last_instance_id_removed_for_testing());
+
+  EXPECT_TRUE(manager->CanUseGuestInstanceID(3));
+
+  manager->AddGuest(3, web_contents3.get());
+  manager->RemoveGuest(1);
+  EXPECT_FALSE(manager->CanUseGuestInstanceID(1));
+  EXPECT_FALSE(manager->CanUseGuestInstanceID(2));
+
+  EXPECT_EQ(2, manager->last_instance_id_removed_for_testing());
+  manager->RemoveGuest(3);
+  EXPECT_EQ(3, manager->last_instance_id_removed_for_testing());
+
+  EXPECT_FALSE(manager->CanUseGuestInstanceID(1));
+  EXPECT_FALSE(manager->CanUseGuestInstanceID(2));
+  EXPECT_FALSE(manager->CanUseGuestInstanceID(3));
+
+  EXPECT_EQ(0u, manager->GetRemovedInstanceIdSize());
+}