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

sync/engine/syncer_types.h

Index: sync/engine/syncer_types.h
diff --git a/sync/engine/syncer_types.h b/sync/engine/syncer_types.h
index c34621e710a2c75a1b00ccded0833d2a78a5623e..5639d98f7183e2e5b3a23f24068d82a6fe22be81 100644
--- a/sync/engine/syncer_types.h
+++ b/sync/engine/syncer_types.h
@@ -6,26 +6,10 @@
 #define SYNC_ENGINE_SYNCER_TYPES_H_
 #pragma once
 
-#include <map>
-#include <string>
-#include <vector>
-
-#include "base/observer_list.h"
-#include "sync/syncable/model_type.h"
-
-namespace syncable {
-class Id;
-}
-
 // The intent of this is to keep all shared data types and enums for the syncer
 // in a single place without having dependencies between other files.
 namespace browser_sync {
 
-namespace sessions {
-struct SyncSessionSnapshot;
-}
-class Syncer;
-
 enum UpdateAttemptResponse {
   // Update was applied or safely ignored.
   SUCCESS,
@@ -98,61 +82,6 @@ enum VerifyCommitResult {
   VERIFY_OK,
 };
 
-struct SyncEngineEvent {
-  enum EventCause {
-    ////////////////////////////////////////////////////////////////
-    // Sent on entry of Syncer state machine
-    SYNC_CYCLE_BEGIN,
-
-    // SyncerCommand generated events.
-    STATUS_CHANGED,
-
-    // We have reached the SYNCER_END state in the main sync loop.
-    SYNC_CYCLE_ENDED,
-
-    ////////////////////////////////////////////////////////////////
-    // Generated in response to specific protocol actions or events.
-
-    // New token in updated_token.
-    UPDATED_TOKEN,
-
-    // This is sent after the Syncer (and SyncerThread) have initiated self
-    // halt due to no longer being permitted to communicate with the server.
-    // The listener should sever the sync / browser connections and delete sync
-    // data (i.e. as if the user clicked 'Stop Syncing' in the browser.
-    STOP_SYNCING_PERMANENTLY,
-
-    // These events are sent to indicate when we know the clearing of
-    // server data have failed or succeeded.
-    CLEAR_SERVER_DATA_SUCCEEDED,
-    CLEAR_SERVER_DATA_FAILED,
-
-    // This event is sent when we receive an actionable error. It is upto
-    // the listeners to figure out the action to take using the snapshot sent.
-    ACTIONABLE_ERROR,
-  };
-
-  explicit SyncEngineEvent(EventCause cause);
-  ~SyncEngineEvent();
-
-  EventCause what_happened;
-
-  // The last session used for syncing.
-  const sessions::SyncSessionSnapshot* snapshot;
-
-  // Update-Client-Auth returns a new token for sync use.
-  std::string updated_token;
-};
-
-class SyncEngineEventListener {
- public:
-  // TODO(tim): Consider splitting this up to multiple callbacks, rather than
-  // have to do Event e(type); OnSyncEngineEvent(e); at all callsites,
-  virtual void OnSyncEngineEvent(const SyncEngineEvent& event) = 0;
- protected:
-  virtual ~SyncEngineEventListener() {}
-};
-
 }  // namespace browser_sync
 
 #endif  // SYNC_ENGINE_SYNCER_TYPES_H_