[Sync] Add per-navigation timestamps/unique ids to tab sync.

chrome/browser/sync/glue/session_model_associator_unittest.cc

Index: chrome/browser/sync/glue/session_model_associator_unittest.cc
diff --git a/chrome/browser/sync/glue/session_model_associator_unittest.cc b/chrome/browser/sync/glue/session_model_associator_unittest.cc
index 4d5a018d77f962b8318634208d95cdb8de5c80e5..7a1dbf15b5f4097c94fbb49910e5ca91802d3a29 100644
--- a/chrome/browser/sync/glue/session_model_associator_unittest.cc
+++ b/chrome/browser/sync/glue/session_model_associator_unittest.cc
@@ -15,7 +15,6 @@
 #include "chrome/common/url_constants.h"
 #include "chrome/test/base/profile_mock.h"
 #include "content/public/browser/navigation_entry.h"
-#include "content/public/browser/navigation_entry.h"
 #include "content/public/browser/notification_details.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/common/page_transition_types.h"
@@ -23,10 +22,12 @@
 #include "sync/protocol/session_specifics.pb.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
+#include "sync/util/time.h"
 
 using content::BrowserThread;
 using testing::NiceMock;
 using testing::Return;
+using testing::_;
 
 namespace browser_sync {
 
@@ -34,12 +35,36 @@ class SyncSessionModelAssociatorTest : public testing::Test {
  public:
   SyncSessionModelAssociatorTest()
       : ui_thread_(BrowserThread::UI, &message_loop_),
-        sync_service_(&profile_) {}
-  virtual void SetUp() OVERRIDE {
-    model_associator_.reset(new SessionModelAssociator(&sync_service_, true));
+        sync_service_(&profile_),
+        model_associator_(&sync_service_, true) {}
+
+  // Helper methods to avoid having to friend individual tests.
+  bool GetFavicon(std::string page_url, std::string* favicon) {
+    return model_associator_.GetSyncedFaviconForPageURL(page_url, favicon);
+  }
+
+  void LoadTabFavicon(const sync_pb::SessionTab& tab) {
+    model_associator_.LoadForeignTabFavicon(tab);
+  }
+
+  size_t NumFavicons() {
+    return model_associator_.NumFaviconsForTesting();
+  }
+
+  void DecrementFavicon(std::string url) {
+    model_associator_.DecrementAndCleanFaviconForURL(url);
   }
-  virtual void TearDown() OVERRIDE {
-    model_associator_.reset();
+
+  void AssociateTabContents(const SyncedWindowDelegate& window,
+                            const SyncedTabDelegate& new_tab,
+                            SyncedSessionTab* prev_tab,
+                            sync_pb::SessionTab* sync_tab,
+                            GURL* new_url) {
+    model_associator_.AssociateTabContents(window,
+                                           new_tab,
+                                           prev_tab,
+                                           sync_tab,
+                                           new_url);
   }
 
  protected:
@@ -47,7 +72,7 @@ class SyncSessionModelAssociatorTest : public testing::Test {
   content::TestBrowserThread ui_thread_;
   NiceMock<ProfileMock> profile_;
   NiceMock<ProfileSyncServiceMock> sync_service_;
-  scoped_ptr<SessionModelAssociator> model_associator_;
+  SessionModelAssociator model_associator_;
 };
 
 TEST_F(SyncSessionModelAssociatorTest, SessionWindowHasNoTabsToSync) {
@@ -66,7 +91,7 @@ TEST_F(SyncSessionModelAssociatorTest, SessionWindowHasNoTabsToSync) {
 }
 
 TEST_F(SyncSessionModelAssociatorTest, ShouldSyncSessionTab) {
-  SessionTab tab;
+  SyncedSessionTab tab;
   ASSERT_FALSE(ShouldSyncSessionTab(tab));
   TabNavigation nav(0, GURL(chrome::kChromeUINewTabURL),
                     content::Referrer(GURL("about:referrer"),
@@ -88,7 +113,7 @@ TEST_F(SyncSessionModelAssociatorTest, ShouldSyncSessionTab) {
 
 TEST_F(SyncSessionModelAssociatorTest,
        ShouldSyncSessionTabIgnoresFragmentForNtp) {
-  SessionTab tab;
+  SyncedSessionTab tab;
   ASSERT_FALSE(ShouldSyncSessionTab(tab));
   TabNavigation nav(0, GURL(std::string(chrome::kChromeUINewTabURL) +
                             "#bookmarks"),
@@ -142,13 +167,12 @@ TEST_F(SyncSessionModelAssociatorTest, PopulateSessionTab) {
   tab_s.set_pinned(true);
   tab_s.set_extension_app_id("app_id");
   sync_pb::TabNavigation* navigation = tab_s.add_navigation();
-  navigation->set_index(12);
   navigation->set_virtual_url("http://foo/1");
   navigation->set_referrer("referrer");
   navigation->set_title("title");
   navigation->set_page_transition(sync_pb::TabNavigation_PageTransition_TYPED);
 
-  SessionTab tab;
+  SyncedSessionTab tab;
   tab.tab_id.set_id(5);  // Expected to be set by the SyncedSessionTracker.
   SessionModelAssociator::PopulateSessionTabFromSpecifics(
       tab_s, base::Time(), &tab);
@@ -157,7 +181,6 @@ TEST_F(SyncSessionModelAssociatorTest, PopulateSessionTab) {
   ASSERT_EQ(3, tab.current_navigation_index);
   ASSERT_TRUE(tab.pinned);
   ASSERT_EQ("app_id", tab.extension_app_id);
-  ASSERT_EQ(12, tab.navigations[0].index());
   ASSERT_EQ(GURL("referrer"), tab.navigations[0].referrer().url);
   ASSERT_EQ(string16(ASCIIToUTF16("title")), tab.navigations[0].title());
   ASSERT_EQ(content::PAGE_TRANSITION_TYPED, tab.navigations[0].transition());
@@ -214,10 +237,26 @@ TEST_F(SyncSessionModelAssociatorTest, TabNodePool) {
 
 namespace {
 
+class SyncedWindowDelegateMock : public SyncedWindowDelegate {
+ public:
+  SyncedWindowDelegateMock() {}
+  virtual ~SyncedWindowDelegateMock() {}
+  MOCK_CONST_METHOD0(HasWindow, bool());
+  MOCK_CONST_METHOD0(GetSessionId, SessionID::id_type());
+  MOCK_CONST_METHOD0(GetTabCount, int());
+  MOCK_CONST_METHOD0(GetActiveIndex, int());
+  MOCK_CONST_METHOD0(IsApp, bool());
+  MOCK_CONST_METHOD0(IsTypeTabbed, bool());
+  MOCK_CONST_METHOD0(IsTypePopup, bool());
+  MOCK_CONST_METHOD1(IsTabPinned, bool(const SyncedTabDelegate* tab));
+  MOCK_CONST_METHOD1(GetTabAt, SyncedTabDelegate*(int index));
+  MOCK_CONST_METHOD1(GetTabIdAt, SessionID::id_type(int index));
+};
+
 class SyncedTabDelegateMock : public SyncedTabDelegate {
  public:
   SyncedTabDelegateMock() {}
-  ~SyncedTabDelegateMock() {}
+  virtual ~SyncedTabDelegateMock() {}
 
   MOCK_CONST_METHOD0(GetWindowId, SessionID::id_type());
   MOCK_CONST_METHOD0(GetSessionId, SessionID::id_type());
@@ -263,7 +302,7 @@ TEST_F(SyncSessionModelAssociatorTest, TriggerSessionRefresh) {
   SyncRefreshListener refresh_listener;
 
   EXPECT_FALSE(refresh_listener.notified_of_refresh());
-  model_associator_->AttemptSessionsDataRefresh();
+  model_associator_.AttemptSessionsDataRefresh();
   EXPECT_TRUE(refresh_listener.notified_of_refresh());
 }
 
@@ -278,7 +317,7 @@ TEST_F(SyncSessionModelAssociatorTest, ValidTabs) {
       Return((content::NavigationEntry *)NULL));
   EXPECT_CALL(tab_mock, GetEntryCount()).WillRepeatedly(Return(1));
   EXPECT_CALL(tab_mock, GetPendingEntryIndex()).WillRepeatedly(Return(-1));
-  EXPECT_FALSE(model_associator_->ShouldSyncTab(tab_mock));
+  EXPECT_FALSE(model_associator_.ShouldSyncTab(tab_mock));
 
   // A chrome:// entry isn't valid.
   scoped_ptr<content::NavigationEntry> entry(
@@ -289,7 +328,7 @@ TEST_F(SyncSessionModelAssociatorTest, ValidTabs) {
   EXPECT_CALL(tab_mock, GetEntryAtIndex(0)).WillRepeatedly(Return(entry.get()));
   EXPECT_CALL(tab_mock, GetEntryCount()).WillRepeatedly(Return(1));
   EXPECT_CALL(tab_mock, GetPendingEntryIndex()).WillRepeatedly(Return(-1));
-  EXPECT_FALSE(model_associator_->ShouldSyncTab(tab_mock));
+  EXPECT_FALSE(model_associator_.ShouldSyncTab(tab_mock));
 
   // A file:// entry isn't valid, even in addition to another entry.
   scoped_ptr<content::NavigationEntry> entry2(
@@ -302,7 +341,7 @@ TEST_F(SyncSessionModelAssociatorTest, ValidTabs) {
       Return(entry2.get()));
   EXPECT_CALL(tab_mock, GetEntryCount()).WillRepeatedly(Return(2));
   EXPECT_CALL(tab_mock, GetPendingEntryIndex()).WillRepeatedly(Return(-1));
-  EXPECT_FALSE(model_associator_->ShouldSyncTab(tab_mock));
+  EXPECT_FALSE(model_associator_.ShouldSyncTab(tab_mock));
 
   // Add a valid scheme entry to tab, making the tab valid.
   scoped_ptr<content::NavigationEntry> entry3(
@@ -318,7 +357,482 @@ TEST_F(SyncSessionModelAssociatorTest, ValidTabs) {
       Return(entry3.get()));
   EXPECT_CALL(tab_mock, GetEntryCount()).WillRepeatedly(Return(3));
   EXPECT_CALL(tab_mock, GetPendingEntryIndex()).WillRepeatedly(Return(-1));
-  EXPECT_TRUE(model_associator_->ShouldSyncTab(tab_mock));
+  EXPECT_TRUE(model_associator_.ShouldSyncTab(tab_mock));
+}
+
+// Create tab specifics with an empty favicon. Ensure it gets ignored and not
+// stored into the synced favicon lookups.
+TEST_F(SyncSessionModelAssociatorTest, LoadEmptyFavicon) {
+  std::string favicon = "";
+  std::string favicon_url = "http://www.faviconurl.com/favicon.ico";
+  std::string page_url = "http://www.faviconurl.com/page.html";
+  sync_pb::SessionTab tab;
+  tab.set_favicon(favicon);
+  tab.set_favicon_source(favicon_url);
+  tab.set_favicon_type(sync_pb::SessionTab::TYPE_WEB_FAVICON);
+  sync_pb::TabNavigation* navigation = tab.add_navigation();
+  navigation->set_virtual_url(page_url);
+  tab.set_current_navigation_index(0);
+
+  std::string synced_favicon;
+  EXPECT_FALSE(GetFavicon(page_url, &synced_favicon));
+  EXPECT_TRUE(synced_favicon.empty());
+  LoadTabFavicon(tab);
+  EXPECT_FALSE(GetFavicon(page_url, &synced_favicon));
+  EXPECT_TRUE(synced_favicon.empty());
+}
+
+// Create tab specifics with a non-web favicon. Ensure it gets ignored and not
+// stored into the synced favicon lookups.
+TEST_F(SyncSessionModelAssociatorTest, LoadNonWebFavicon) {
+  std::string favicon = "these are icon synced_favicon";
+  std::string favicon_url = "http://www.faviconurl.com/favicon.ico";
+  std::string page_url = "http://www.faviconurl.com/page.html";
+  sync_pb::SessionTab tab;
+  tab.set_favicon(favicon);
+  tab.set_favicon_source(favicon_url);
+  // Set favicon type to an unsupported value (1 == WEB_FAVICON).
+   tab.mutable_unknown_fields()->AddVarint(9, 2);
+  sync_pb::TabNavigation* navigation = tab.add_navigation();
+  navigation->set_virtual_url(page_url);
+  tab.set_current_navigation_index(0);
+
+  std::string synced_favicon;
+  EXPECT_FALSE(GetFavicon(page_url, &synced_favicon));
+  EXPECT_TRUE(synced_favicon.empty());
+  LoadTabFavicon(tab);
+  EXPECT_FALSE(GetFavicon(page_url, &synced_favicon));
+  EXPECT_TRUE(synced_favicon.empty());
+}
+
+// Create tab specifics with a valid favicon. Ensure it gets stored in the
+// synced favicon lookups and is accessible by the page url.
+TEST_F(SyncSessionModelAssociatorTest, LoadValidFavicon) {
+  std::string favicon = "these are icon synced_favicon";
+  std::string favicon_url = "http://www.faviconurl.com/favicon.ico";
+  std::string page_url = "http://www.faviconurl.com/page.html";
+  sync_pb::SessionTab tab;
+  tab.set_favicon(favicon);
+  tab.set_favicon_source(favicon_url);
+  tab.set_favicon_type(sync_pb::SessionTab::TYPE_WEB_FAVICON);
+  sync_pb::TabNavigation* navigation = tab.add_navigation();
+  navigation->set_virtual_url(page_url);
+  tab.set_current_navigation_index(0);
+
+  std::string synced_favicon;
+  EXPECT_FALSE(GetFavicon(page_url, &synced_favicon));
+  EXPECT_TRUE(synced_favicon.empty());
+  LoadTabFavicon(tab);
+  EXPECT_TRUE(GetFavicon(page_url, &synced_favicon));
+  ASSERT_FALSE(synced_favicon.empty());
+  EXPECT_EQ(favicon, synced_favicon);
+}
+
+// Create tab specifics with a valid favicon, load it, then load tab specifics
+// with a new favicon for the same favicon source but different page. Ensure the
+// new favicon overwrites the old favicon for both page urls.
+TEST_F(SyncSessionModelAssociatorTest, UpdateValidFavicon) {
+  std::string favicon_url = "http://www.faviconurl.com/favicon.ico";
+
+  std::string favicon = "these are icon synced_favicon";
+  std::string page_url = "http://www.faviconurl.com/page.html";
+  sync_pb::SessionTab tab;
+  tab.set_favicon(favicon);
+  tab.set_favicon_source(favicon_url);
+  tab.set_favicon_type(sync_pb::SessionTab::TYPE_WEB_FAVICON);
+  sync_pb::TabNavigation* navigation = tab.add_navigation();
+  navigation->set_virtual_url(page_url);
+  tab.set_current_navigation_index(0);
+
+  std::string synced_favicon;
+  EXPECT_FALSE(GetFavicon(page_url, &synced_favicon));
+  EXPECT_TRUE(synced_favicon.empty());
+  LoadTabFavicon(tab);
+  EXPECT_TRUE(GetFavicon(page_url, &synced_favicon));
+  ASSERT_FALSE(synced_favicon.empty());
+  EXPECT_EQ(favicon, synced_favicon);
+
+  // Now have a new page with same favicon source but newer favicon data.
+  std::string favicon2 = "these are new icon synced_favicon";
+  std::string page_url2 = "http://www.faviconurl.com/page2.html";
+  sync_pb::SessionTab tab2;
+  tab2.set_favicon(favicon2);
+  tab2.set_favicon_source(favicon_url);
+  tab2.set_favicon_type(sync_pb::SessionTab::TYPE_WEB_FAVICON);
+  sync_pb::TabNavigation* navigation2 = tab2.add_navigation();
+  navigation2->set_virtual_url(page_url2);
+  tab2.set_current_navigation_index(0);
+
+  // Verify the favicons for both pages match the newest favicon.
+  synced_favicon.clear();
+  EXPECT_FALSE(GetFavicon(page_url2, &synced_favicon));
+  EXPECT_TRUE(synced_favicon.empty());
+  LoadTabFavicon(tab2);
+  EXPECT_TRUE(GetFavicon(page_url2, &synced_favicon));
+  ASSERT_FALSE(synced_favicon.empty());
+  EXPECT_EQ(favicon2, synced_favicon);
+  EXPECT_NE(favicon, synced_favicon);
+  synced_favicon.clear();
+  EXPECT_TRUE(GetFavicon(page_url, &synced_favicon));
+  ASSERT_FALSE(synced_favicon.empty());
+  EXPECT_EQ(favicon2, synced_favicon);
+  EXPECT_NE(favicon, synced_favicon);
+}
+
+// Ensure that favicon cleanup cleans up favicons no longer being used and
+// doesn't touch those favicons still in use.
+TEST_F(SyncSessionModelAssociatorTest, FaviconCleanup) {
+  EXPECT_EQ(NumFavicons(), 0U);
+
+  std::string double_favicon = "these are icon synced_favicon";
+  std::string double_favicon_url = "http://www.faviconurl.com/favicon.ico";
+  std::string page_url = "http://www.faviconurl.com/page.html";
+  sync_pb::SessionTab tab;
+  tab.set_favicon(double_favicon);
+  tab.set_favicon_source(double_favicon_url);
+  tab.set_favicon_type(sync_pb::SessionTab::TYPE_WEB_FAVICON);
+  sync_pb::TabNavigation* navigation = tab.add_navigation();
+  navigation->set_virtual_url(page_url);
+  tab.set_current_navigation_index(0);
+  LoadTabFavicon(tab);
+  EXPECT_EQ(1U, NumFavicons());
+
+  // Add another page using the first favicon.
+  std::string page_url2 = "http://www.faviconurl.com/page2.html";
+  tab.mutable_navigation(0)->set_virtual_url(page_url2);
+  LoadTabFavicon(tab);
+  EXPECT_EQ(1U, NumFavicons());
+
+  // Add a favicon with a single user.
+  std::string single_favicon = "different favicon synced_favicon";
+  std::string single_favicon_url = "http://www.single_favicon_page.com/x.ico";
+  std::string single_favicon_page = "http://www.single_favicon_page.com/x.html";
+  tab.set_favicon(single_favicon);
+  tab.set_favicon_source(single_favicon_url);
+  tab.mutable_navigation(0)->set_virtual_url(single_favicon_page);
+  LoadTabFavicon(tab);
+  EXPECT_EQ(2U, NumFavicons());
+
+  // Decrementing a favicon used by one page should remove it.
+  std::string synced_favicon;
+  EXPECT_TRUE(GetFavicon(single_favicon_page, &synced_favicon));
+  EXPECT_EQ(synced_favicon, single_favicon);
+  DecrementFavicon(single_favicon_page);
+  synced_favicon.clear();
+  EXPECT_FALSE(GetFavicon(single_favicon_page, &synced_favicon));
+  EXPECT_TRUE(synced_favicon.empty());
+  EXPECT_EQ(1U, NumFavicons());
+
+  // Decrementing a favicon used by two pages shouldn't remove it.
+  synced_favicon.clear();
+  EXPECT_TRUE(GetFavicon(page_url, &synced_favicon));
+  EXPECT_EQ(synced_favicon, double_favicon);
+  synced_favicon.clear();
+  EXPECT_TRUE(GetFavicon(page_url2, &synced_favicon));
+  EXPECT_EQ(synced_favicon, double_favicon);
+  DecrementFavicon(page_url);
+  EXPECT_EQ(1U, NumFavicons());
+  synced_favicon.clear();
+  EXPECT_TRUE(GetFavicon(page_url, &synced_favicon));
+  EXPECT_EQ(synced_favicon, double_favicon);
+  synced_favicon.clear();
+  EXPECT_TRUE(GetFavicon(page_url2, &synced_favicon));
+  EXPECT_EQ(synced_favicon, double_favicon);
+  EXPECT_EQ(1U, NumFavicons());
+
+  // Attempting to decrement a page that's already removed should do nothing.
+  DecrementFavicon(single_favicon_page);
+  EXPECT_EQ(1U, NumFavicons());
+
+  // Attempting to decrement an empty url should do nothing.
+  DecrementFavicon("");
+  EXPECT_EQ(1U, NumFavicons());
+
+  // Decrementing the second and only remaining page should remove the favicon.
+  // Both pages that referred to it should now fail to look up their favicon.
+  DecrementFavicon(page_url2);
+  synced_favicon.clear();
+  EXPECT_FALSE(GetFavicon(page_url, &synced_favicon));
+  EXPECT_TRUE(synced_favicon.empty());
+  EXPECT_EQ(0U, NumFavicons());
+  synced_favicon.clear();
+  EXPECT_FALSE(GetFavicon(page_url2, &synced_favicon));
+  EXPECT_TRUE(synced_favicon.empty());
+  EXPECT_EQ(0U, NumFavicons());
+}
+
+// Ensure new tabs have all new timestamps set.
+TEST_F(SyncSessionModelAssociatorTest, AssociateNewTab) {
+  NiceMock<SyncedWindowDelegateMock> window_mock;
+  EXPECT_CALL(window_mock, IsTabPinned(_)).WillRepeatedly(Return(false));
+
+  // Create a tab with three valid entries.
+  NiceMock<SyncedTabDelegateMock> tab_mock;
+  EXPECT_CALL(tab_mock, GetSessionId()).WillRepeatedly(Return(0));
+  scoped_ptr<content::NavigationEntry> entry1(
+      content::NavigationEntry::Create());
+  entry1->SetVirtualURL(GURL("http://www.google.com"));
+  scoped_ptr<content::NavigationEntry> entry2(
+      content::NavigationEntry::Create());
+  entry2->SetVirtualURL(GURL("http://www.noodle.com"));
+  scoped_ptr<content::NavigationEntry> entry3(
+      content::NavigationEntry::Create());
+  entry3->SetVirtualURL(GURL("http://www.doodle.com"));
+  EXPECT_CALL(tab_mock, GetCurrentEntryIndex()).WillRepeatedly(Return(2));
+  EXPECT_CALL(tab_mock, GetEntryAtIndex(0)).WillRepeatedly(
+      Return(entry1.get()));
+  EXPECT_CALL(tab_mock, GetEntryAtIndex(1)).WillRepeatedly(
+      Return(entry2.get()));
+  EXPECT_CALL(tab_mock, GetEntryAtIndex(2)).WillRepeatedly(
+      Return(entry3.get()));
+  EXPECT_CALL(tab_mock, GetEntryCount()).WillRepeatedly(Return(3));
+  EXPECT_CALL(tab_mock, GetPendingEntryIndex()).WillRepeatedly(Return(-1));
+
+  // This tab is new, so prev_tab is the default SyncedSessionTab object.
+  SyncedSessionTab prev_tab;
+  prev_tab.tab_id.set_id(0);
+
+  sync_pb::SessionTab sync_tab;
+  GURL new_url;
+  int64 now = TimeToProtoTime(base::Time::Now());
+  AssociateTabContents(window_mock, tab_mock, &prev_tab, &sync_tab, &new_url);
+
+  EXPECT_EQ(new_url, entry3->GetVirtualURL());
+  ASSERT_EQ(3, sync_tab.navigation_size());
+  EXPECT_EQ(entry1->GetVirtualURL().spec(),
+            sync_tab.navigation(0).virtual_url());
+  EXPECT_EQ(entry2->GetVirtualURL().spec(),
+            sync_tab.navigation(1).virtual_url());
+  EXPECT_EQ(entry3->GetVirtualURL().spec(),
+            sync_tab.navigation(2).virtual_url());
+  EXPECT_EQ(2, sync_tab.current_navigation_index());
+  EXPECT_LE(now, sync_tab.navigation(0).timestamp());
+  EXPECT_LE(now, sync_tab.navigation(1).timestamp());
+  EXPECT_LE(now, sync_tab.navigation(2).timestamp());
+}
+
+// Ensure we preserve old timestamps when the entries don't change.
+TEST_F(SyncSessionModelAssociatorTest, AssociateExistingTab) {
+  NiceMock<SyncedWindowDelegateMock> window_mock;
+  EXPECT_CALL(window_mock, IsTabPinned(_)).WillRepeatedly(Return(false));
+
+  // Create a tab with three valid entries.
+  NiceMock<SyncedTabDelegateMock> tab_mock;
+  EXPECT_CALL(tab_mock, GetSessionId()).WillRepeatedly(Return(0));
+  scoped_ptr<content::NavigationEntry> entry1(
+      content::NavigationEntry::Create());
+  entry1->SetVirtualURL(GURL("http://www.google.com"));
+  scoped_ptr<content::NavigationEntry> entry2(
+      content::NavigationEntry::Create());
+  entry2->SetVirtualURL(GURL("http://www.noodle.com"));
+  scoped_ptr<content::NavigationEntry> entry3(
+      content::NavigationEntry::Create());
+  entry3->SetVirtualURL(GURL("http://www.doodle.com"));
+  EXPECT_CALL(tab_mock, GetCurrentEntryIndex()).WillRepeatedly(Return(2));
+  EXPECT_CALL(tab_mock, GetEntryAtIndex(0)).WillRepeatedly(
+      Return(entry1.get()));
+  EXPECT_CALL(tab_mock, GetEntryAtIndex(1)).WillRepeatedly(
+      Return(entry2.get()));
+  EXPECT_CALL(tab_mock, GetEntryAtIndex(2)).WillRepeatedly(
+      Return(entry3.get()));
+  EXPECT_CALL(tab_mock, GetEntryCount()).WillRepeatedly(Return(3));
+  EXPECT_CALL(tab_mock, GetPendingEntryIndex()).WillRepeatedly(Return(-1));
+
+  // This tab is new, so prev_tab is the default SyncedSessionTab object.
+  SyncedSessionTab prev_tab;
+  prev_tab.tab_id.set_id(0);
+
+  // The initial AssociateTabContents call builds the prev_tab.
+  sync_pb::SessionTab sync_tab;
+  GURL new_url;
+  AssociateTabContents(window_mock, tab_mock, &prev_tab, &sync_tab, &new_url);
+
+  // Override the timestamps to arbitrary old values we can compare against.
+  prev_tab.synced_tab_navigations[0].set_timestamp(ProtoTimeToTime(1));
+  prev_tab.synced_tab_navigations[1].set_timestamp(ProtoTimeToTime(2));
+  prev_tab.synced_tab_navigations[2].set_timestamp(ProtoTimeToTime(3));
+
+  // Now re-associate with the same data.
+  AssociateTabContents(window_mock, tab_mock, &prev_tab, &sync_tab, &new_url);
+
+  EXPECT_EQ(new_url, entry3->GetVirtualURL());
+  ASSERT_EQ(3, sync_tab.navigation_size());
+  EXPECT_EQ(entry1->GetVirtualURL().spec(),
+            sync_tab.navigation(0).virtual_url());
+  EXPECT_EQ(entry2->GetVirtualURL().spec(),
+            sync_tab.navigation(1).virtual_url());
+  EXPECT_EQ(entry3->GetVirtualURL().spec(),
+            sync_tab.navigation(2).virtual_url());
+  EXPECT_EQ(2, sync_tab.current_navigation_index());
+  EXPECT_EQ(1, sync_tab.navigation(0).timestamp());
+  EXPECT_EQ(2, sync_tab.navigation(1).timestamp());
+  EXPECT_EQ(3, sync_tab.navigation(2).timestamp());
+  EXPECT_EQ(3U, prev_tab.navigations.size());
+  EXPECT_EQ(3U, prev_tab.synced_tab_navigations.size());
+}
+
+// Ensure we add a fresh timestamp for new entries appended to the end.
+TEST_F(SyncSessionModelAssociatorTest, AssociateAppendedTab) {
+    NiceMock<SyncedWindowDelegateMock> window_mock;
+  EXPECT_CALL(window_mock, IsTabPinned(_)).WillRepeatedly(Return(false));
+
+  // Create a tab with three valid entries.
+  NiceMock<SyncedTabDelegateMock> tab_mock;
+  EXPECT_CALL(tab_mock, GetSessionId()).WillRepeatedly(Return(0));
+  scoped_ptr<content::NavigationEntry> entry1(
+      content::NavigationEntry::Create());
+  entry1->SetVirtualURL(GURL("http://www.google.com"));
+  scoped_ptr<content::NavigationEntry> entry2(
+      content::NavigationEntry::Create());
+  entry2->SetVirtualURL(GURL("http://www.noodle.com"));
+  scoped_ptr<content::NavigationEntry> entry3(
+      content::NavigationEntry::Create());
+  entry3->SetVirtualURL(GURL("http://www.doodle.com"));
+  EXPECT_CALL(tab_mock, GetCurrentEntryIndex()).WillRepeatedly(Return(2));
+  EXPECT_CALL(tab_mock, GetEntryAtIndex(0)).WillRepeatedly(
+      Return(entry1.get()));
+  EXPECT_CALL(tab_mock, GetEntryAtIndex(1)).WillRepeatedly(
+      Return(entry2.get()));
+  EXPECT_CALL(tab_mock, GetEntryAtIndex(2)).WillRepeatedly(
+      Return(entry3.get()));
+  EXPECT_CALL(tab_mock, GetEntryCount()).WillRepeatedly(Return(3));
+  EXPECT_CALL(tab_mock, GetPendingEntryIndex()).WillRepeatedly(Return(-1));
+
+  // This tab is new, so prev_tab is the default SyncedSessionTab object.
+  SyncedSessionTab prev_tab;
+  prev_tab.tab_id.set_id(0);
+
+  // The initial AssociateTabContents call builds the prev_tab.
+  sync_pb::SessionTab sync_tab;
+  GURL new_url;
+  AssociateTabContents(window_mock, tab_mock, &prev_tab, &sync_tab, &new_url);
+
+  // Override the timestamps to arbitrary old values we can compare against.
+  prev_tab.synced_tab_navigations[0].set_timestamp(ProtoTimeToTime(1));
+  prev_tab.synced_tab_navigations[1].set_timestamp(ProtoTimeToTime(2));
+  prev_tab.synced_tab_navigations[2].set_timestamp(ProtoTimeToTime(3));
+
+  // Add a new entry and change the current navigation index.
+  scoped_ptr<content::NavigationEntry> entry4(
+      content::NavigationEntry::Create());
+  entry4->SetVirtualURL(GURL("http://www.poodle.com"));
+  EXPECT_CALL(tab_mock, GetEntryAtIndex(3)).WillRepeatedly(
+      Return(entry4.get()));
+  EXPECT_CALL(tab_mock, GetEntryCount()).WillRepeatedly(Return(4));
+  EXPECT_CALL(tab_mock, GetCurrentEntryIndex()).WillRepeatedly(Return(3));
+
+  // The new entry should have a timestamp later than this.
+  int64 now = TimeToProtoTime(base::Time::Now());
+
+  // Now re-associate with the new version.
+  AssociateTabContents(window_mock, tab_mock, &prev_tab, &sync_tab, &new_url);
+
+  EXPECT_EQ(new_url, entry4->GetVirtualURL());
+  ASSERT_EQ(4, sync_tab.navigation_size());
+  EXPECT_EQ(entry1->GetVirtualURL().spec(),
+            sync_tab.navigation(0).virtual_url());
+  EXPECT_EQ(entry2->GetVirtualURL().spec(),
+            sync_tab.navigation(1).virtual_url());
+  EXPECT_EQ(entry3->GetVirtualURL().spec(),
+            sync_tab.navigation(2).virtual_url());
+  EXPECT_EQ(entry4->GetVirtualURL().spec(),
+            sync_tab.navigation(3).virtual_url());
+  EXPECT_EQ(3, sync_tab.current_navigation_index());
+  EXPECT_EQ(1, sync_tab.navigation(0).timestamp());
+  EXPECT_EQ(2, sync_tab.navigation(1).timestamp());
+  EXPECT_EQ(3, sync_tab.navigation(2).timestamp());
+  EXPECT_LE(now, sync_tab.navigation(3).timestamp());
+  EXPECT_EQ(4U, prev_tab.navigations.size());
+  EXPECT_EQ(4U, prev_tab.synced_tab_navigations.size());
+}
+
+// We shouldn't get confused when old/new entries from the previous tab have
+// been pruned in the new tab. Timestamps for old entries we move back to in the
+// navigation stack should be refreshed.
+TEST_F(SyncSessionModelAssociatorTest, AssociatePrunedTab) {
+    NiceMock<SyncedWindowDelegateMock> window_mock;
+  EXPECT_CALL(window_mock, IsTabPinned(_)).WillRepeatedly(Return(false));
+
+  // Create a tab with four valid entries.
+  NiceMock<SyncedTabDelegateMock> tab_mock;
+  EXPECT_CALL(tab_mock, GetSessionId()).WillRepeatedly(Return(0));
+  scoped_ptr<content::NavigationEntry> entry1(
+      content::NavigationEntry::Create());
+  entry1->SetVirtualURL(GURL("http://www.google.com"));
+  scoped_ptr<content::NavigationEntry> entry2(
+      content::NavigationEntry::Create());
+  entry2->SetVirtualURL(GURL("http://www.noodle.com"));
+  scoped_ptr<content::NavigationEntry> entry3(
+      content::NavigationEntry::Create());
+  entry3->SetVirtualURL(GURL("http://www.doodle.com"));
+  scoped_ptr<content::NavigationEntry> entry4(
+      content::NavigationEntry::Create());
+  entry4->SetVirtualURL(GURL("http://www.poodle.com"));
+  EXPECT_CALL(tab_mock, GetCurrentEntryIndex()).WillRepeatedly(Return(3));
+  EXPECT_CALL(tab_mock, GetEntryAtIndex(0)).WillRepeatedly(
+      Return(entry1.get()));
+  EXPECT_CALL(tab_mock, GetEntryAtIndex(1)).WillRepeatedly(
+      Return(entry2.get()));
+  EXPECT_CALL(tab_mock, GetEntryAtIndex(2)).WillRepeatedly(
+      Return(entry3.get()));
+  EXPECT_CALL(tab_mock, GetEntryAtIndex(3)).WillRepeatedly(
+      Return(entry4.get()));
+  EXPECT_CALL(tab_mock, GetEntryCount()).WillRepeatedly(Return(4));
+  EXPECT_CALL(tab_mock, GetPendingEntryIndex()).WillRepeatedly(Return(-1));
+
+  // This tab is new, so prev_tab is the default SyncedSessionTab object.
+  SyncedSessionTab prev_tab;
+  prev_tab.tab_id.set_id(0);
+
+  // The initial AssociateTabContents call builds the prev_tab.
+  sync_pb::SessionTab sync_tab;
+  GURL new_url;
+  AssociateTabContents(window_mock, tab_mock, &prev_tab, &sync_tab, &new_url);
+
+  // Override the timestamps to arbitrary old values we can compare against.
+  prev_tab.synced_tab_navigations[0].set_timestamp(ProtoTimeToTime(1));
+  prev_tab.synced_tab_navigations[1].set_timestamp(ProtoTimeToTime(2));
+  prev_tab.synced_tab_navigations[2].set_timestamp(ProtoTimeToTime(3));
+  prev_tab.synced_tab_navigations[2].set_timestamp(ProtoTimeToTime(4));
+
+  // Reset new tab to have the oldest entry pruned, the current navigation
+  // set to entry3, and a new entry added in place of entry4.
+  testing::Mock::VerifyAndClearExpectations(&tab_mock);
+  EXPECT_CALL(tab_mock, GetCurrentEntryIndex()).WillRepeatedly(Return(1));
+  EXPECT_CALL(tab_mock, GetEntryAtIndex(0)).WillRepeatedly(
+      Return(entry2.get()));
+  EXPECT_CALL(tab_mock, GetEntryAtIndex(1)).WillRepeatedly(
+      Return(entry3.get()));
+  scoped_ptr<content::NavigationEntry> entry5(
+      content::NavigationEntry::Create());
+  entry5->SetVirtualURL(GURL("http://www.noogle.com"));
+  EXPECT_CALL(tab_mock, GetEntryAtIndex(2)).WillRepeatedly(
+      Return(entry5.get()));
+  EXPECT_CALL(tab_mock, GetEntryCount()).WillRepeatedly(Return(3));
+  EXPECT_CALL(tab_mock, GetPendingEntryIndex()).WillRepeatedly(Return(-1));
+
+  // The new entry should have a timestamp later than this.
+  int64 now = TimeToProtoTime(base::Time::Now());
+
+  // Now re-associate with the new version.
+  AssociateTabContents(window_mock, tab_mock, &prev_tab, &sync_tab, &new_url);
+
+  // Only entry2's timestamp should be preserved. The new entry should have a
+  // new timestamp.
+  EXPECT_EQ(new_url, entry3->GetVirtualURL());
+  ASSERT_EQ(3, sync_tab.navigation_size());
+  EXPECT_EQ(entry2->GetVirtualURL().spec(),
+            sync_tab.navigation(0).virtual_url());
+  EXPECT_EQ(entry3->GetVirtualURL().spec(),
+            sync_tab.navigation(1).virtual_url());
+  EXPECT_EQ(entry5->GetVirtualURL().spec(),
+            sync_tab.navigation(2).virtual_url());
+  EXPECT_EQ(1, sync_tab.current_navigation_index());
+  EXPECT_EQ(2, sync_tab.navigation(0).timestamp());
+  EXPECT_LE(now, sync_tab.navigation(1).timestamp());
+  EXPECT_LE(now, sync_tab.navigation(2).timestamp());
+  EXPECT_EQ(3U, prev_tab.navigations.size());
+  EXPECT_EQ(3U, prev_tab.synced_tab_navigations.size());
 }
 
 }  // namespace browser_sync