[Sync] Convert SyncSessionSnapshot to a copy-able class.

chrome/browser/sync/profile_sync_service.h

Index: chrome/browser/sync/profile_sync_service.h
diff --git a/chrome/browser/sync/profile_sync_service.h b/chrome/browser/sync/profile_sync_service.h
index 0abf55d3861d9f1942dac3c3f3fad84b5d1b8385..3a779ba20e6402ecb872df561a6156887177f8d2 100644
--- a/chrome/browser/sync/profile_sync_service.h
+++ b/chrome/browser/sync/profile_sync_service.h
@@ -48,7 +48,7 @@ class ChangeProcessor;
 class DataTypeManager;
 class JsController;
 class SessionModelAssociator;
-namespace sessions { struct SyncSessionSnapshot; }
+namespace sessions { class SyncSessionSnapshot; }
 }
 
 namespace sync_api {
@@ -360,7 +360,7 @@ class ProfileSyncService : public browser_sync::SyncFrontend,
   // ProfileSyncServiceHarness.  Figure out a different way to expose
   // this info to that class, and remove these functions.
 
-  virtual const browser_sync::sessions::SyncSessionSnapshot*
+  virtual browser_sync::sessions::SyncSessionSnapshot
       GetLastSessionSnapshot() const;
 
   // Returns whether or not the underlying sync engine has made any