[Sync] Initialize pre-existing navs to zero timestamp

When we restore a session at restart, from a recently closed tab, or from other
devices, we don't want to assign the current timestamp to all navigations. Only
the current navigation should have the current timestamp, all others should be
zero'd out.

BUG=98892
TEST=unit tests


Review URL: http://codereview.chromium.org/10381019

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@135699 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 13 insertions, 3 deletions

diff --git a/chrome/browser/sync/glue/session_model_associator.cc b/chrome/browser/sync/glue/session_model_associator.cc
index 1848a6f..d0e875c 100644
--- a/chrome/browser/sync/glue/session_model_associator.cc
+++ b/chrome/browser/sync/glue/session_model_associator.cc
@@ -510,6 +510,15 @@ void SessionModelAssociator::AssociateTabContents(
         // over navigations, so the subsequent navigation entries may need their
         // old timestamps preserved.
         ++prev_nav_iter;
+      } else if (current_index != i &&
+                 prev_tab->synced_tab_navigations.empty()) {
+        // If this is a new tab, and has more than one navigation, we don't
+        // actually want to assign the current timestamp to other navigations.
+        // Override the timestamp to 0 in that case.
+        // Note: this is primarily to handle restoring sessions at restart,
+        // opening recently closed tabs, or opening tabs from other devices.
+        // Only the current navigation should have a timestamp in those cases.
+        sync_nav->set_timestamp(0);
       }
     }
   }
diff --git a/chrome/browser/sync/glue/session_model_associator_unittest.cc b/chrome/browser/sync/glue/session_model_associator_unittest.cc
index 11709d3..38a9673 100644
--- a/chrome/browser/sync/glue/session_model_associator_unittest.cc
+++ b/chrome/browser/sync/glue/session_model_associator_unittest.cc
@@ -561,7 +561,8 @@ TEST_F(SyncSessionModelAssociatorTest, FaviconCleanup) {
   EXPECT_EQ(0U, NumFavicons());
 }
 
-// Ensure new tabs have all new timestamps set.
+// Ensure new tabs have the current timestamp set for the current navigation,
+// while other navigations have timestamp zero.
 TEST_F(SyncSessionModelAssociatorTest, AssociateNewTab) {
   NiceMock<SyncedWindowDelegateMock> window_mock;
   EXPECT_CALL(window_mock, IsTabPinned(_)).WillRepeatedly(Return(false));
@@ -606,8 +607,8 @@ TEST_F(SyncSessionModelAssociatorTest, AssociateNewTab) {
   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(0, sync_tab.navigation(0).timestamp());
+  EXPECT_LE(0, sync_tab.navigation(1).timestamp());
   EXPECT_LE(now, sync_tab.navigation(2).timestamp());
 }