Depend on stored sync session GUID for Android.

chrome/browser/sync/glue/session_model_associator.cc

Index: chrome/browser/sync/glue/session_model_associator.cc
diff --git a/chrome/browser/sync/glue/session_model_associator.cc b/chrome/browser/sync/glue/session_model_associator.cc
index e34133d95f155a729f4051b4e5ce574b252efefe..9dddbb43c4d23d24a97e96f645365c103402c538 100644
--- a/chrome/browser/sync/glue/session_model_associator.cc
+++ b/chrome/browser/sync/glue/session_model_associator.cc
@@ -48,8 +48,6 @@
 #include "base/linux_util.h"
 #elif defined(OS_WIN)
 #include <windows.h>
-#elif defined(OS_ANDROID)
-#include "sync/util/session_utils_android.h"
 #endif
 
 using content::BrowserThread;
@@ -643,6 +641,16 @@ syncer::SyncError SessionModelAssociator::AssociateModels(
 
       local_session_syncid_ = write_node.GetId();
     }
+#if defined(OS_ANDROID)
+    std::string persisted_machine_tag;

[Nicolas Zea, 2012/11/16 18:55:20]

I don't think you need this variable, doesn't current_machine_tag_ already hold
the same string?

[nyquist, 2012/12/04 01:55:05]

Done.

+    if (pref_service_)
+      persisted_machine_tag = pref_service_->GetString(kSyncSessionsGUID);
+
+    std::string transaction_tag = GetMachineTagFromTransaction(&trans);
+    if (persisted_machine_tag.compare(transaction_tag) != 0) {
+      DeleteForeignSession(transaction_tag);
+    }
+#endif
   }
 
   // Check if anything has changed on the client side.
@@ -690,19 +698,7 @@ void SessionModelAssociator::InitializeCurrentMachineTag(
     DVLOG(1) << "Restoring persisted session sync guid: "
              << persisted_guid;
   } else {
-    syncer::syncable::Directory* dir =
-        trans->GetWrappedWriteTrans()->directory();
-    current_machine_tag_ = "session_sync";
-#if defined(OS_ANDROID)
-    const std::string android_id = syncer::internal::GetAndroidId();
-    // There are reports that sometimes the android_id can't be read. Those
-    // are supposed to be fixed as of Gingerbread, but if it happens we fall
-    // back to use the same GUID generation as on other platforms.
-    current_machine_tag_.append(android_id.empty() ?
-                                    dir->cache_guid() : android_id);
-#else
-    current_machine_tag_.append(dir->cache_guid());
-#endif
+    current_machine_tag_ = GetMachineTagFromTransaction(trans);
     DVLOG(1) << "Creating session sync guid: " << current_machine_tag_;
     if (pref_service_)
       pref_service_->SetString(kSyncSessionsGUID, current_machine_tag_);
@@ -1282,6 +1278,14 @@ bool SessionModelAssociator::TabHasValidEntry(
   return found_valid_url;
 }
 
+std::string SessionModelAssociator::GetMachineTagFromTransaction(

[Nicolas Zea, 2012/11/16 18:55:20]

Since this is basically a static helper method, I think having it at the top of
the file in an anon namespace is better than a private member.

[nyquist, 2012/12/04 01:55:05]

Done.

+    syncer::WriteTransaction* trans) {
+  syncer::syncable::Directory* dir = trans->GetWrappedWriteTrans()->directory();
+  std::string machine_tag = "session_sync";
+  machine_tag.append(dir->cache_guid());
+  return machine_tag;
+}
+
 // If this functionality changes, SyncedSession::ShouldSyncSessionTab should be
 // modified to match.
 bool SessionModelAssociator::ShouldSyncTab(const SyncedTabDelegate& tab) const {