Reland of [Sync] Put session tracker in charge of maintaining local state.

components/sync_sessions/synced_session_tracker_unittest.cc

 // Copyright 2012 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 "components/sync_sessions/synced_session_tracker.h"
 
 #include "base/rand_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 #include "components/sessions/core/serialized_navigation_entry_test_helper.h"
 #include "components/sync_sessions/fake_sync_sessions_client.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace sync_sessions {
 
 namespace {
 
 const char kValidUrl[] = "http://www.example.com";
 const char kInvalidUrl[] = "invalid.url";
+const char kTag[] = "tag";
+const char kTag2[] = "tag2";
+const char kTag3[] = "tag3";
+const char kTitle[] = "title";
 
 }  // namespace
 
 class SyncedSessionTrackerTest : public testing::Test {
  public:
   SyncedSessionTrackerTest() : tracker_(&sessions_client_) {}
   ~SyncedSessionTrackerTest() override {}
 
   SyncedSessionTracker* GetTracker() { return &tracker_; }
+  TabNodePool* GetTabNodePool() { return &tracker_.local_tab_pool_; }
 
  private:
   FakeSyncSessionsClient sessions_client_;
   SyncedSessionTracker tracker_;
 };
 
 TEST_F(SyncedSessionTrackerTest, GetSession) {
-  SyncedSession* session1 = GetTracker()->GetSession("tag");
-  SyncedSession* session2 = GetTracker()->GetSession("tag2");
-  ASSERT_EQ(session1, GetTracker()->GetSession("tag"));
+  SyncedSession* session1 = GetTracker()->GetSession(kTag);
+  SyncedSession* session2 = GetTracker()->GetSession(kTag2);
+  ASSERT_EQ(session1, GetTracker()->GetSession(kTag));
   ASSERT_NE(session1, session2);
   // Should clean up memory on its own.
 }
 
 TEST_F(SyncedSessionTrackerTest, GetTabUnmapped) {
-  sessions::SessionTab* tab = GetTracker()->GetTab("tag", 0, 0);
-  ASSERT_EQ(tab, GetTracker()->GetTab("tag", 0, 0));
+  sessions::SessionTab* tab = GetTracker()->GetTab(kTag, 0);
+  ASSERT_EQ(tab, GetTracker()->GetTab(kTag, 0));
   // Should clean up memory on its own.
 }
 
 TEST_F(SyncedSessionTrackerTest, PutWindowInSession) {
-  GetTracker()->PutWindowInSession("tag", 0);
-  SyncedSession* session = GetTracker()->GetSession("tag");
+  GetTracker()->PutWindowInSession(kTag, 0);
+  SyncedSession* session = GetTracker()->GetSession(kTag);
   ASSERT_EQ(1U, session->windows.size());
   // Should clean up memory on its own.
 }
 
 TEST_F(SyncedSessionTrackerTest, PutTabInWindow) {
-  GetTracker()->PutWindowInSession("tag", 10);
-  GetTracker()->PutTabInWindow("tag", 10, 15,
+  GetTracker()->PutWindowInSession(kTag, 10);
+  GetTracker()->PutTabInWindow(kTag, 10, 15,
                                0);  // win id 10, tab id 15, tab ind 0.
-  SyncedSession* session = GetTracker()->GetSession("tag");
+  SyncedSession* session = GetTracker()->GetSession(kTag);
   ASSERT_EQ(1U, session->windows.size());
   ASSERT_EQ(1U, session->windows[10]->tabs.size());
-  ASSERT_EQ(GetTracker()->GetTab("tag", 15, 1),
+  ASSERT_EQ(GetTracker()->GetTab(kTag, 15),
             session->windows[10]->tabs[0].get());
   // Should clean up memory on its own.
 }
 
 TEST_F(SyncedSessionTrackerTest, LookupAllForeignSessions) {
   std::vector<const SyncedSession*> sessions;
   ASSERT_FALSE(GetTracker()->LookupAllForeignSessions(
       &sessions, SyncedSessionTracker::PRESENTABLE));
-  GetTracker()->GetSession("tag1");
-  GetTracker()->PutWindowInSession("tag1", 0);
-  GetTracker()->PutTabInWindow("tag1", 0, 15, 0);
-  sessions::SessionTab* tab = GetTracker()->GetTab("tag1", 15, 1);
+  GetTracker()->GetSession(kTag);
+  GetTracker()->PutWindowInSession(kTag, 0);
+  GetTracker()->PutTabInWindow(kTag, 0, 15, 0);
+  sessions::SessionTab* tab = GetTracker()->GetTab(kTag, 15);
   ASSERT_TRUE(tab);
   tab->navigations.push_back(
       sessions::SerializedNavigationEntryTestHelper::CreateNavigation(kValidUrl,
-                                                                      "title"));
-  GetTracker()->GetSession("tag2");
-  GetTracker()->GetSession("tag3");
-  GetTracker()->PutWindowInSession("tag3", 0);
-  GetTracker()->PutTabInWindow("tag3", 0, 15, 0);
-  tab = GetTracker()->GetTab("tag3", 15, 1);
+                                                                      kTitle));
+  GetTracker()->GetSession(kTag2);
+  GetTracker()->GetSession(kTag3);
+  GetTracker()->PutWindowInSession(kTag3, 0);
+  GetTracker()->PutTabInWindow(kTag3, 0, 15, 0);
+  tab = GetTracker()->GetTab(kTag3, 15);
   ASSERT_TRUE(tab);
   tab->navigations.push_back(
       sessions::SerializedNavigationEntryTestHelper::CreateNavigation(
-          kInvalidUrl, "title"));
+          kInvalidUrl, kTitle));
   ASSERT_TRUE(GetTracker()->LookupAllForeignSessions(
       &sessions, SyncedSessionTracker::PRESENTABLE));
   // Only the session with a valid window and tab gets returned.
   ASSERT_EQ(1U, sessions.size());
-  ASSERT_EQ("tag1", sessions[0]->session_tag);
+  ASSERT_EQ(kTag, sessions[0]->session_tag);
 
   ASSERT_TRUE(GetTracker()->LookupAllForeignSessions(
       &sessions, SyncedSessionTracker::RAW));
   ASSERT_EQ(3U, sessions.size());
 }
 
 TEST_F(SyncedSessionTrackerTest, LookupSessionWindows) {
   std::vector<const sessions::SessionWindow*> windows;
-  ASSERT_FALSE(GetTracker()->LookupSessionWindows("tag1", &windows));
-  GetTracker()->GetSession("tag1");
-  GetTracker()->PutWindowInSession("tag1", 0);
-  GetTracker()->PutWindowInSession("tag1", 2);
-  GetTracker()->GetSession("tag2");
-  GetTracker()->PutWindowInSession("tag2", 0);
-  GetTracker()->PutWindowInSession("tag2", 2);
-  ASSERT_TRUE(GetTracker()->LookupSessionWindows("tag1", &windows));
-  ASSERT_EQ(2U, windows.size());  // Only windows from tag1 session.
+  ASSERT_FALSE(GetTracker()->LookupSessionWindows(kTag, &windows));
+  GetTracker()->GetSession(kTag);
+  GetTracker()->PutWindowInSession(kTag, 0);
+  GetTracker()->PutWindowInSession(kTag, 2);
+  GetTracker()->GetSession(kTag2);
+  GetTracker()->PutWindowInSession(kTag2, 0);
+  GetTracker()->PutWindowInSession(kTag2, 2);
+  ASSERT_TRUE(GetTracker()->LookupSessionWindows(kTag, &windows));
+  ASSERT_EQ(2U, windows.size());  // Only windows from kTag session.
   ASSERT_NE((sessions::SessionWindow*)nullptr, windows[0]);
   ASSERT_NE((sessions::SessionWindow*)nullptr, windows[1]);
   ASSERT_NE(windows[1], windows[0]);
 }
 
 TEST_F(SyncedSessionTrackerTest, LookupSessionTab) {
   const sessions::SessionTab* tab;
-  ASSERT_FALSE(GetTracker()->LookupSessionTab("tag1", 5, &tab));
-  GetTracker()->GetSession("tag1");
-  GetTracker()->PutWindowInSession("tag1", 0);
-  GetTracker()->PutTabInWindow("tag1", 0, 5, 0);
-  ASSERT_TRUE(GetTracker()->LookupSessionTab("tag1", 5, &tab));
+  ASSERT_FALSE(GetTracker()->LookupSessionTab(kTag, 5, &tab));
+  GetTracker()->GetSession(kTag);
+  GetTracker()->PutWindowInSession(kTag, 0);
+  GetTracker()->PutTabInWindow(kTag, 0, 5, 0);
+  ASSERT_TRUE(GetTracker()->LookupSessionTab(kTag, 5, &tab));
   ASSERT_NE((sessions::SessionTab*)nullptr, tab);
 }
 
 TEST_F(SyncedSessionTrackerTest, Complex) {
-  const std::string tag1 = "tag";
-  const std::string tag2 = "tag2";
-  const std::string tag3 = "tag3";
   std::vector<sessions::SessionTab *> tabs1, tabs2;
   sessions::SessionTab* temp_tab;
   ASSERT_TRUE(GetTracker()->Empty());
   ASSERT_EQ(0U, GetTracker()->num_synced_sessions());
-  ASSERT_EQ(0U, GetTracker()->num_synced_tabs(tag1));
-  tabs1.push_back(GetTracker()->GetTab(tag1, 0, 0));
-  tabs1.push_back(GetTracker()->GetTab(tag1, 1, 1));
-  tabs1.push_back(GetTracker()->GetTab(tag1, 2, 2));
-  ASSERT_EQ(3U, GetTracker()->num_synced_tabs(tag1));
-  ASSERT_EQ(1U, GetTracker()->num_synced_sessions());
-  temp_tab = GetTracker()->GetTab(tag1, 0, 0);  // Already created.
-  ASSERT_EQ(3U, GetTracker()->num_synced_tabs(tag1));
-  ASSERT_EQ(1U, GetTracker()->num_synced_sessions());
+  ASSERT_EQ(0U, GetTracker()->num_synced_tabs(kTag));
+  tabs1.push_back(GetTracker()->GetTab(kTag, 0));
+  tabs1.push_back(GetTracker()->GetTab(kTag, 1));
+  tabs1.push_back(GetTracker()->GetTab(kTag, 2));
+  ASSERT_EQ(3U, GetTracker()->num_synced_tabs(kTag));
+  ASSERT_EQ(0U, GetTracker()->num_synced_sessions());
+  temp_tab = GetTracker()->GetTab(kTag, 0);  // Already created.
+  ASSERT_EQ(3U, GetTracker()->num_synced_tabs(kTag));
+  ASSERT_EQ(0U, GetTracker()->num_synced_sessions());
   ASSERT_EQ(tabs1[0], temp_tab);
-  tabs2.push_back(GetTracker()->GetTab(tag2, 0, 0));
-  ASSERT_EQ(1U, GetTracker()->num_synced_tabs(tag2));
-  ASSERT_EQ(2U, GetTracker()->num_synced_sessions());
-  ASSERT_FALSE(GetTracker()->DeleteSession(tag3));
+  tabs2.push_back(GetTracker()->GetTab(kTag2, 0));
+  ASSERT_EQ(1U, GetTracker()->num_synced_tabs(kTag2));
+  ASSERT_EQ(0U, GetTracker()->num_synced_sessions());
+  ASSERT_FALSE(GetTracker()->DeleteForeignSession(kTag3));
 
-  SyncedSession* session = GetTracker()->GetSession(tag1);
-  SyncedSession* session2 = GetTracker()->GetSession(tag2);
-  SyncedSession* session3 = GetTracker()->GetSession(tag3);
+  SyncedSession* session = GetTracker()->GetSession(kTag);
+  SyncedSession* session2 = GetTracker()->GetSession(kTag2);
+  SyncedSession* session3 = GetTracker()->GetSession(kTag3);
   session3->device_type = SyncedSession::TYPE_OTHER;
   ASSERT_EQ(3U, GetTracker()->num_synced_sessions());
 
   ASSERT_TRUE(session);
   ASSERT_TRUE(session2);
   ASSERT_TRUE(session3);
   ASSERT_NE(session, session2);
   ASSERT_NE(session2, session3);
-  ASSERT_TRUE(GetTracker()->DeleteSession(tag3));
+  ASSERT_TRUE(GetTracker()->DeleteForeignSession(kTag3));
   ASSERT_EQ(2U, GetTracker()->num_synced_sessions());
 
-  GetTracker()->PutWindowInSession(tag1, 0);           // Create a window.
-  GetTracker()->PutTabInWindow(tag1, 0, 2, 0);         // No longer unmapped.
-  ASSERT_EQ(3U, GetTracker()->num_synced_tabs(tag1));  // Has not changed.
+  GetTracker()->PutWindowInSession(kTag, 0);           // Create a window.
+  GetTracker()->PutTabInWindow(kTag, 0, 2, 0);         // No longer unmapped.
+  ASSERT_EQ(3U, GetTracker()->num_synced_tabs(kTag));  // Has not changed.
 
   const sessions::SessionTab* tab_ptr;
-  ASSERT_TRUE(GetTracker()->LookupSessionTab(tag1, 0, &tab_ptr));
+  ASSERT_TRUE(GetTracker()->LookupSessionTab(kTag, 0, &tab_ptr));
   ASSERT_EQ(tab_ptr, tabs1[0]);
-  ASSERT_TRUE(GetTracker()->LookupSessionTab(tag1, 2, &tab_ptr));
+  ASSERT_TRUE(GetTracker()->LookupSessionTab(kTag, 2, &tab_ptr));
   ASSERT_EQ(tab_ptr, tabs1[2]);
-  ASSERT_FALSE(GetTracker()->LookupSessionTab(tag1, 3, &tab_ptr));
+  ASSERT_FALSE(GetTracker()->LookupSessionTab(kTag, 3, &tab_ptr));
   ASSERT_FALSE(tab_ptr);
 
   std::vector<const sessions::SessionWindow*> windows;
-  ASSERT_TRUE(GetTracker()->LookupSessionWindows(tag1, &windows));
+  ASSERT_TRUE(GetTracker()->LookupSessionWindows(kTag, &windows));
   ASSERT_EQ(1U, windows.size());
-  ASSERT_TRUE(GetTracker()->LookupSessionWindows(tag2, &windows));
+  ASSERT_TRUE(GetTracker()->LookupSessionWindows(kTag2, &windows));
   ASSERT_EQ(0U, windows.size());
 
   // The sessions don't have valid tabs, lookup should not succeed.
   std::vector<const SyncedSession*> sessions;
   ASSERT_FALSE(GetTracker()->LookupAllForeignSessions(
       &sessions, SyncedSessionTracker::PRESENTABLE));
   ASSERT_TRUE(GetTracker()->LookupAllForeignSessions(
       &sessions, SyncedSessionTracker::RAW));
   ASSERT_EQ(2U, sessions.size());
 
   GetTracker()->Clear();
-  ASSERT_EQ(0U, GetTracker()->num_synced_tabs(tag1));
-  ASSERT_EQ(0U, GetTracker()->num_synced_tabs(tag2));
+  ASSERT_EQ(0U, GetTracker()->num_synced_tabs(kTag));
+  ASSERT_EQ(0U, GetTracker()->num_synced_tabs(kTag2));
   ASSERT_EQ(0U, GetTracker()->num_synced_sessions());
 }
 
 TEST_F(SyncedSessionTrackerTest, ManyGetTabs) {
   ASSERT_TRUE(GetTracker()->Empty());
   const int kMaxSessions = 10;
   const int kMaxTabs = 1000;
   const int kMaxAttempts = 10000;
   for (int j = 0; j < kMaxSessions; ++j) {
     std::string tag = base::StringPrintf("tag%d", j);
     for (int i = 0; i < kMaxAttempts; ++i) {
       // More attempts than tabs means we'll sometimes get the same tabs,
       // sometimes have to allocate new tabs.
       int rand_tab_num = base::RandInt(0, kMaxTabs);
-      sessions::SessionTab* tab =
-          GetTracker()->GetTab(tag, rand_tab_num, rand_tab_num + 1);
+      sessions::SessionTab* tab = GetTracker()->GetTab(tag, rand_tab_num + 1);
       ASSERT_TRUE(tab);
     }
   }
 }
 
-TEST_F(SyncedSessionTrackerTest, LookupTabNodeIds) {
+TEST_F(SyncedSessionTrackerTest, LookupForeignTabNodeIds) {
   std::set<int> result;
-  std::string tag1 = "session1";
-  std::string tag2 = "session2";
-  std::string tag3 = "session3";
 
-  GetTracker()->GetTab(tag1, 1, 1);
-  GetTracker()->GetTab(tag1, 2, 2);
-  GetTracker()->LookupTabNodeIds(tag1, &result);
+  GetTracker()->OnTabNodeSeen(kTag, 1);
+  GetTracker()->OnTabNodeSeen(kTag, 2);
+  GetTracker()->LookupForeignTabNodeIds(kTag, &result);
   EXPECT_EQ(2U, result.size());
   EXPECT_FALSE(result.end() == result.find(1));
   EXPECT_FALSE(result.end() == result.find(2));
-  GetTracker()->LookupTabNodeIds(tag2, &result);
+  GetTracker()->LookupForeignTabNodeIds(kTag2, &result);
   EXPECT_TRUE(result.empty());
 
-  GetTracker()->PutWindowInSession(tag1, 0);
-  GetTracker()->PutTabInWindow(tag1, 0, 3, 0);
-  GetTracker()->LookupTabNodeIds(tag1, &result);
+  GetTracker()->PutWindowInSession(kTag, 0);
+  GetTracker()->PutTabInWindow(kTag, 0, 3, 0);
+  GetTracker()->LookupForeignTabNodeIds(kTag, &result);
   EXPECT_EQ(2U, result.size());
 
-  GetTracker()->GetTab(tag1, 3, 3);
-  GetTracker()->LookupTabNodeIds(tag1, &result);
+  GetTracker()->OnTabNodeSeen(kTag, 3);
+  GetTracker()->LookupForeignTabNodeIds(kTag, &result);
   EXPECT_EQ(3U, result.size());
   EXPECT_FALSE(result.end() == result.find(3));
 
-  GetTracker()->GetTab(tag2, 1, 21);
-  GetTracker()->GetTab(tag2, 2, 22);
-  GetTracker()->LookupTabNodeIds(tag2, &result);
+  GetTracker()->OnTabNodeSeen(kTag2, 21);
+  GetTracker()->OnTabNodeSeen(kTag2, 22);
+  GetTracker()->LookupForeignTabNodeIds(kTag2, &result);
   EXPECT_EQ(2U, result.size());
   EXPECT_FALSE(result.end() == result.find(21));
   EXPECT_FALSE(result.end() == result.find(22));
-  GetTracker()->LookupTabNodeIds(tag1, &result);
+  GetTracker()->LookupForeignTabNodeIds(kTag, &result);
   EXPECT_EQ(3U, result.size());
   EXPECT_FALSE(result.end() == result.find(1));
   EXPECT_FALSE(result.end() == result.find(2));
 
-  GetTracker()->LookupTabNodeIds(tag3, &result);
+  GetTracker()->LookupForeignTabNodeIds(kTag3, &result);
   EXPECT_TRUE(result.empty());
-  GetTracker()->PutWindowInSession(tag3, 1);
-  GetTracker()->PutTabInWindow(tag3, 1, 5, 0);
-  GetTracker()->LookupTabNodeIds(tag3, &result);
+  GetTracker()->PutWindowInSession(kTag3, 1);
+  GetTracker()->PutTabInWindow(kTag3, 1, 5, 0);
+  GetTracker()->LookupForeignTabNodeIds(kTag3, &result);
   EXPECT_TRUE(result.empty());
-  EXPECT_FALSE(GetTracker()->DeleteSession(tag3));
-  GetTracker()->LookupTabNodeIds(tag3, &result);
+  EXPECT_FALSE(GetTracker()->DeleteForeignSession(kTag3));
+  GetTracker()->LookupForeignTabNodeIds(kTag3, &result);
   EXPECT_TRUE(result.empty());
 
-  EXPECT_FALSE(GetTracker()->DeleteSession(tag1));
-  GetTracker()->LookupTabNodeIds(tag1, &result);
+  EXPECT_FALSE(GetTracker()->DeleteForeignSession(kTag));
+  GetTracker()->LookupForeignTabNodeIds(kTag, &result);
   EXPECT_TRUE(result.empty());
-  GetTracker()->LookupTabNodeIds(tag2, &result);
+  GetTracker()->LookupForeignTabNodeIds(kTag2, &result);
   EXPECT_EQ(2U, result.size());
   EXPECT_FALSE(result.end() == result.find(21));
   EXPECT_FALSE(result.end() == result.find(22));
 
-  GetTracker()->GetTab(tag2, 1, 21);
-  GetTracker()->GetTab(tag2, 2, 23);
-  GetTracker()->LookupTabNodeIds(tag2, &result);
+  GetTracker()->OnTabNodeSeen(kTag2, 21);
+  GetTracker()->OnTabNodeSeen(kTag2, 23);
+  GetTracker()->LookupForeignTabNodeIds(kTag2, &result);
   EXPECT_EQ(3U, result.size());
   EXPECT_FALSE(result.end() == result.find(21));
   EXPECT_FALSE(result.end() == result.find(22));
   EXPECT_FALSE(result.end() == result.find(23));
 
-  EXPECT_FALSE(GetTracker()->DeleteSession(tag2));
-  GetTracker()->LookupTabNodeIds(tag2, &result);
+  EXPECT_FALSE(GetTracker()->DeleteForeignSession(kTag2));
+  GetTracker()->LookupForeignTabNodeIds(kTag2, &result);
   EXPECT_TRUE(result.empty());
 }
 
 TEST_F(SyncedSessionTrackerTest, SessionTracking) {
   ASSERT_TRUE(GetTracker()->Empty());
-  std::string tag1 = "tag1";
-  std::string tag2 = "tag2";
 
   // Create some session information that is stale.
-  SyncedSession* session1 = GetTracker()->GetSession(tag1);
-  GetTracker()->PutWindowInSession(tag1, 0);
-  GetTracker()->PutTabInWindow(tag1, 0, 0, 0);
-  GetTracker()->PutTabInWindow(tag1, 0, 1, 1);
-  GetTracker()->GetTab(tag1, 2, 3U)->window_id.set_id(0);  // Will be unmapped.
-  GetTracker()->GetTab(tag1, 3, 4U)->window_id.set_id(0);  // Will be unmapped.
-  GetTracker()->PutWindowInSession(tag1, 1);
-  GetTracker()->PutTabInWindow(tag1, 1, 4, 0);
-  GetTracker()->PutTabInWindow(tag1, 1, 5, 1);
+  SyncedSession* session1 = GetTracker()->GetSession(kTag);
+  GetTracker()->PutWindowInSession(kTag, 0);
+  GetTracker()->PutTabInWindow(kTag, 0, 0, 0);
+  GetTracker()->PutTabInWindow(kTag, 0, 1, 1);
+  GetTracker()->GetTab(kTag, 2)->window_id.set_id(0);  // Will be unmapped.
+  GetTracker()->GetTab(kTag, 3)->window_id.set_id(0);  // Will be unmapped.
+  GetTracker()->PutWindowInSession(kTag, 1);
+  GetTracker()->PutTabInWindow(kTag, 1, 4, 0);
+  GetTracker()->PutTabInWindow(kTag, 1, 5, 1);
   ASSERT_EQ(2U, session1->windows.size());
   ASSERT_EQ(2U, session1->windows[0]->tabs.size());
   ASSERT_EQ(2U, session1->windows[1]->tabs.size());
-  ASSERT_EQ(6U, GetTracker()->num_synced_tabs(tag1));
+  ASSERT_EQ(6U, GetTracker()->num_synced_tabs(kTag));
 
   // Create a session that should not be affected.
-  SyncedSession* session2 = GetTracker()->GetSession(tag2);
-  GetTracker()->PutWindowInSession(tag2, 2);
-  GetTracker()->PutTabInWindow(tag2, 2, 1, 0);
+  SyncedSession* session2 = GetTracker()->GetSession(kTag2);
+  GetTracker()->PutWindowInSession(kTag2, 2);
+  GetTracker()->PutTabInWindow(kTag2, 2, 1, 0);
   ASSERT_EQ(1U, session2->windows.size());
   ASSERT_EQ(1U, session2->windows[2]->tabs.size());
-  ASSERT_EQ(1U, GetTracker()->num_synced_tabs(tag2));
+  ASSERT_EQ(1U, GetTracker()->num_synced_tabs(kTag2));
 
   // Reset tracking and get the current windows/tabs.
   // We simulate moving a tab from one window to another, then closing the
   // first window (including its one remaining tab), and opening a new tab
   // on the remaining window.
 
   // New tab, arrived before meta node so unmapped.
-  GetTracker()->GetTab(tag1, 6, 7U);
-  GetTracker()->ResetSessionTracking(tag1);
-  GetTracker()->PutWindowInSession(tag1, 0);
-  GetTracker()->PutTabInWindow(tag1, 0, 0, 0);
+  GetTracker()->GetTab(kTag, 6);
+  GetTracker()->ResetSessionTracking(kTag);
+  GetTracker()->PutWindowInSession(kTag, 0);
+  GetTracker()->PutTabInWindow(kTag, 0, 0, 0);
   // Tab 1 is closed.
-  GetTracker()->PutTabInWindow(tag1, 0, 2, 1);  // No longer unmapped.
+  GetTracker()->PutTabInWindow(kTag, 0, 2, 1);  // No longer unmapped.
   // Tab 3 was unmapped and does not get used.
-  GetTracker()->PutTabInWindow(tag1, 0, 4, 2);  // Moved from window 1.
+  GetTracker()->PutTabInWindow(kTag, 0, 4, 2);  // Moved from window 1.
   // Window 1 was closed, along with tab 5.
-  GetTracker()->PutTabInWindow(tag1, 0, 6, 3);  // No longer unmapped.
+  GetTracker()->PutTabInWindow(kTag, 0, 6, 3);  // No longer unmapped.
   // Session 2 should not be affected.
-  GetTracker()->CleanupSession(tag1);
+  GetTracker()->CleanupForeignSession(kTag);
 
   // Verify that only those parts of the session not owned have been removed.
   ASSERT_EQ(1U, session1->windows.size());
   ASSERT_EQ(4U, session1->windows[0]->tabs.size());
   ASSERT_EQ(1U, session2->windows.size());
   ASSERT_EQ(1U, session2->windows[2]->tabs.size());
   ASSERT_EQ(2U, GetTracker()->num_synced_sessions());
-  ASSERT_EQ(4U, GetTracker()->num_synced_tabs(tag1));
-  ASSERT_EQ(1U, GetTracker()->num_synced_tabs(tag2));
+  ASSERT_EQ(4U, GetTracker()->num_synced_tabs(kTag));
+  ASSERT_EQ(1U, GetTracker()->num_synced_tabs(kTag2));
 
   // All memory should be properly deallocated by destructor for the
   // SyncedSessionTracker.
 }
 
 TEST_F(SyncedSessionTrackerTest, DeleteForeignTab) {
-  std::string session_tag = "session_tag";
-  int tab_id_1 = 1;
-  int tab_id_2 = 2;
-  int tab_node_id_3 = 3;
-  int tab_node_id_4 = 4;
+  int tab_node_id_1 = 1;
+  int tab_node_id_2 = 2;
   std::set<int> result;
 
-  GetTracker()->GetTab(session_tag, tab_id_1, tab_node_id_3);
-  GetTracker()->GetTab(session_tag, tab_id_1, tab_node_id_4);
-  GetTracker()->GetTab(session_tag, tab_id_2, tab_node_id_3);
-  GetTracker()->GetTab(session_tag, tab_id_2, tab_node_id_4);
+  GetTracker()->OnTabNodeSeen(kTag, tab_node_id_1);
+  GetTracker()->OnTabNodeSeen(kTag, tab_node_id_2);
 
-  GetTracker()->LookupTabNodeIds(session_tag, &result);
+  GetTracker()->LookupForeignTabNodeIds(kTag, &result);
   EXPECT_EQ(2U, result.size());
-  EXPECT_TRUE(result.find(tab_node_id_3) != result.end());
-  EXPECT_TRUE(result.find(tab_node_id_4) != result.end());
+  EXPECT_TRUE(result.find(tab_node_id_1) != result.end());
+  EXPECT_TRUE(result.find(tab_node_id_2) != result.end());
 
-  GetTracker()->DeleteForeignTab(session_tag, tab_node_id_3);
-  GetTracker()->LookupTabNodeIds(session_tag, &result);
+  GetTracker()->DeleteForeignTab(kTag, tab_node_id_1);
+  GetTracker()->LookupForeignTabNodeIds(kTag, &result);
   EXPECT_EQ(1U, result.size());
-  EXPECT_TRUE(result.find(tab_node_id_4) != result.end());
+  EXPECT_TRUE(result.find(tab_node_id_2) != result.end());
 
-  GetTracker()->DeleteForeignTab(session_tag, tab_node_id_4);
-  GetTracker()->LookupTabNodeIds(session_tag, &result);
+  GetTracker()->DeleteForeignTab(kTag, tab_node_id_2);
+  GetTracker()->LookupForeignTabNodeIds(kTag, &result);
   EXPECT_TRUE(result.empty());
 }
 
+TEST_F(SyncedSessionTrackerTest, CleanupLocalTabs) {
+  std::set<int> free_node_ids;
+  int tab_node_id = TabNodePool::kInvalidTabNodeID;
+  const int kWindow1 = 1;
+  const int kTabNode1 = 1;
+  const int kTabNode2 = 2;
+  const int kTabNode3 = 3;
+  const int kTab1 = 15;
+  const int kTab2 = 25;
+  const int kTab3 = 35;
+  const int kTabIndex = 0;
+
+  GetTracker()->SetLocalSessionTag(kTag);
+
+  // Start with two restored tab nodes.
+  GetTracker()->ReassociateLocalTab(kTabNode1, kTab1);
+  GetTracker()->ReassociateLocalTab(kTabNode2, kTab2);
+  EXPECT_TRUE(GetTabNodePool()->Empty());
+  EXPECT_FALSE(GetTabNodePool()->Full());
+  EXPECT_EQ(2U, GetTabNodePool()->Capacity());
+
+  // Associate with no tabs. The tab pool should now be full.
+  GetTracker()->ResetSessionTracking(kTag);
+  GetTracker()->CleanupLocalTabs(&free_node_ids);
+  EXPECT_TRUE(free_node_ids.empty());
+  EXPECT_TRUE(GetTabNodePool()->Full());
+
+  // Associate with only 1 tab open. A tab node should be reused.
+  GetTracker()->ResetSessionTracking(kTag);
+  GetTracker()->PutWindowInSession(kTag, kWindow1);
+  GetTracker()->PutTabInWindow(kTag, kWindow1, kTab1, kTabIndex);
+  EXPECT_TRUE(GetTracker()->GetTabNodeForLocalTab(kTab1, &tab_node_id));
+  GetTracker()->CleanupLocalTabs(&free_node_ids);
+  EXPECT_TRUE(free_node_ids.empty());
+
+  // TabNodePool should have one free tab node and one used.
+  EXPECT_EQ(2U, GetTabNodePool()->Capacity());
+  EXPECT_FALSE(GetTabNodePool()->Empty());
+  EXPECT_FALSE(GetTabNodePool()->Full());
+
+  // Simulate a tab opening, which should use the last free tab node.
+  EXPECT_TRUE(GetTracker()->GetTabNodeForLocalTab(kTab2, &tab_node_id));
+  EXPECT_TRUE(GetTabNodePool()->Empty());
+
+  // Simulate another tab opening, which should create a new associated tab
+  // node.
+  EXPECT_FALSE(GetTracker()->GetTabNodeForLocalTab(kTab3, &tab_node_id));
+  EXPECT_EQ(kTabNode3, tab_node_id);
+  EXPECT_EQ(3U, GetTabNodePool()->Capacity());
+  EXPECT_TRUE(GetTabNodePool()->Empty());
+
+  // Fetching the same tab should return the same tab node id.
+  EXPECT_TRUE(GetTracker()->GetTabNodeForLocalTab(kTab3, &tab_node_id));
+  EXPECT_EQ(kTabNode3, tab_node_id);
+  EXPECT_TRUE(GetTabNodePool()->Empty());
+
+  // Associate with no tabs. All tabs should be freed again, and the pool
+  // should now be full.
+  GetTracker()->ResetSessionTracking(kTag);
+  GetTracker()->CleanupLocalTabs(&free_node_ids);
+  EXPECT_TRUE(free_node_ids.empty());
+  EXPECT_TRUE(GetTabNodePool()->Full());
+  EXPECT_FALSE(GetTabNodePool()->Empty());
+}
+
+TEST_F(SyncedSessionTrackerTest, ReassociateTabMapped) {
+  std::set<int> free_node_ids;
+  const int kWindow1 = 1;
+  const int kTabNode = 0;
+  const int kTabIndex = 0;
+  const int kTab1 = 15;
+  const int kTab2 = 25;
+
+  // First create the tab normally.
+  GetTracker()->SetLocalSessionTag(kTag);
+  GetTracker()->ReassociateLocalTab(kTabNode, kTab1);
+
+  // Map it to a window with the same tab id as it was created with.
+  GetTracker()->ResetSessionTracking(kTag);
+  GetTracker()->PutWindowInSession(kTag, kWindow1);
+  GetTracker()->PutTabInWindow(kTag, kWindow1, kTab1, kTabIndex);
+  GetTracker()->CleanupLocalTabs(&free_node_ids);
+  SyncedSession* session = GetTracker()->GetSession(kTag);
+  ASSERT_EQ(1U, session->windows.size());
+  ASSERT_EQ(1U, session->windows[kWindow1]->tabs.size());
+  ASSERT_EQ(GetTracker()->GetTab(kTag, kTab1),
+            session->windows[kWindow1]->tabs[0].get());
+
+  // Then reassociate with a new tab id.
+  GetTracker()->ReassociateLocalTab(kTabNode, kTab2);
+
+  // Reset tracking, and put the new tab id into the window.
+  GetTracker()->ResetSessionTracking(kTag);
+  GetTracker()->PutWindowInSession(kTag, kWindow1);
+  GetTracker()->PutTabInWindow(kTag, kWindow1, kTab2, kTabIndex);
+  GetTracker()->CleanupLocalTabs(&free_node_ids);
+  EXPECT_TRUE(free_node_ids.empty());
+
+  // Now that it's been mapped, it should be accessible both via the
+  // GetSession as well as the GetTab.
+  ASSERT_EQ(GetTracker()->GetTab(kTag, kTab2),
+            session->windows[kWindow1]->tabs[0].get());
+  ASSERT_EQ(session->tab_node_ids.size(),
+            session->tab_node_ids.count(kTabNode));
+  ASSERT_EQ(1U, GetTabNodePool()->Capacity());
+}
+
+TEST_F(SyncedSessionTrackerTest, ReassociateTabUnmapped) {
+  std::set<int> free_node_ids;
+  const int kWindow1 = 1;
+  const int kTabNode = 0;
+  const int kTabIndex = 0;
+  const int kTab1 = 15;
+  const int kTab2 = 25;
+
+  // First create the old tab in an unmapped state.
+  GetTracker()->SetLocalSessionTag(kTag);
+  GetTracker()->ReassociateLocalTab(kTabNode, kTab1);
+
+  // Map it to a window, but reassociated with a new tab id.
+  GetTracker()->ResetSessionTracking(kTag);
+  GetTracker()->ReassociateLocalTab(kTabNode, kTab2);
+  GetTracker()->PutWindowInSession(kTag, kWindow1);
+  GetTracker()->PutTabInWindow(kTag, kWindow1, kTab2, kTabIndex);
+  GetTracker()->CleanupLocalTabs(&free_node_ids);
+  EXPECT_TRUE(free_node_ids.empty());
+
+  // Now that it's been mapped, it should be accessible both via the
+  // GetSession as well as GetTab.
+  SyncedSession* session = GetTracker()->GetSession(kTag);
+  ASSERT_EQ(GetTracker()->GetTab(kTag, kTab2),
+            session->windows[kWindow1]->tabs[0].get());
+  ASSERT_EQ(session->tab_node_ids.size(),
+            session->tab_node_ids.count(kTabNode));
+  ASSERT_EQ(1U, GetTabNodePool()->Capacity());
+}
+
 }  // namespace sync_sessions