[Sync] Refactor non-frontend DTC to handle new API properly.

chrome/browser/sync/glue/generic_change_processor.cc

Index: chrome/browser/sync/glue/generic_change_processor.cc
diff --git a/chrome/browser/sync/glue/generic_change_processor.cc b/chrome/browser/sync/glue/generic_change_processor.cc
index 8a064af20c4d499b27e6799e7d027245416e36b0..eb8e4b45bba969b8e46d68ab387ae37d853a17cb 100644
--- a/chrome/browser/sync/glue/generic_change_processor.cc
+++ b/chrome/browser/sync/glue/generic_change_processor.cc
@@ -17,21 +17,45 @@
 #include "chrome/browser/sync/internal_api/write_transaction.h"
 #include "chrome/browser/sync/unrecoverable_error_handler.h"
 
+using base::AutoLock;
+
 namespace browser_sync {
 
 GenericChangeProcessor::GenericChangeProcessor(
-    SyncableService* local_service,
+    UnrecoverableErrorHandler* error_handler)
+    : ChangeProcessor(error_handler),
+      local_service_(NULL),
+      user_share_(NULL),
+      disconnected_(false) {}
+
+GenericChangeProcessor::GenericChangeProcessor(
     UnrecoverableErrorHandler* error_handler,
+    SyncableService* local_service,
     sync_api::UserShare* user_share)
     : ChangeProcessor(error_handler),
-      local_service_(local_service),
-      user_share_(user_share) {
-  DCHECK(local_service_);
+      local_service_(NULL),
+      user_share_(NULL),
+      disconnected_(false) {
+  Connect(local_service, user_share);
+}
+
+GenericChangeProcessor::~GenericChangeProcessor() {}
+
+// Connect to the syncer and SyncableService specified.
+void GenericChangeProcessor::Connect(SyncableService* local_service,
+                                     sync_api::UserShare* user_share) {
+  AutoLock lock(monitor_lock_);
+  if (disconnected_)
+    return;
+  DCHECK(local_service);
+  local_service_ = local_service;
+  user_share_ = user_share;
 }
 
-GenericChangeProcessor::~GenericChangeProcessor() {
-  // Set to null to ensure it's not used after destruction.
-  local_service_ = NULL;
+void GenericChangeProcessor::Disconnect() {
+  VLOG(1) << "Disconnecting change processor.";
+  AutoLock lock(monitor_lock_);
+  disconnected_ = true;
 }
 
 void GenericChangeProcessor::ApplyChangesFromSyncModel(
@@ -70,7 +94,7 @@ void GenericChangeProcessor::CommitChangesFromSyncModel() {
   if (syncer_changes_.empty())
     return;
   SyncError error = local_service_->ProcessSyncChanges(FROM_HERE,
-                                                        syncer_changes_);
+                                                       syncer_changes_);
   syncer_changes_.clear();
   if (error.IsSet()) {
     error_handler()->OnUnrecoverableError(error.location(), error.message());
@@ -80,6 +104,11 @@ void GenericChangeProcessor::CommitChangesFromSyncModel() {
 SyncError GenericChangeProcessor::GetSyncDataForType(
     syncable::ModelType type,
     SyncDataList* current_sync_data) {
+  AutoLock lock(monitor_lock_);
+  if (disconnected_) {
+    SyncError error(FROM_HERE, "Change processor disconnected.", type);
+    return error;
+  }
   std::string type_name = syncable::ModelTypeToString(type);
   sync_api::ReadTransaction trans(FROM_HERE, share_handle());
   sync_api::ReadNode root(&trans);
@@ -137,6 +166,17 @@ bool AttemptDelete(const SyncChange& change, sync_api::WriteNode* node) {
 SyncError GenericChangeProcessor::ProcessSyncChanges(
     const tracked_objects::Location& from_here,
     const SyncChangeList& list_of_changes) {
+  AutoLock lock(monitor_lock_);
+  if (disconnected_) {
+    syncable::ModelType type;
+    if (list_of_changes.size() > 0) {
+      type = list_of_changes[0].sync_data().GetDataType();
+      local_service_->StopSyncing(type);
+    }
+    SyncError error(FROM_HERE, "Change processor disconnected.",
+                    syncable::UNSPECIFIED);
+    return error;
+  }
   sync_api::WriteTransaction trans(from_here, share_handle());
 
   for (SyncChangeList::const_iterator iter = list_of_changes.begin();
@@ -216,6 +256,11 @@ SyncError GenericChangeProcessor::ProcessSyncChanges(
 bool GenericChangeProcessor::SyncModelHasUserCreatedNodes(
     syncable::ModelType type,
     bool* has_nodes) {
+  AutoLock lock(monitor_lock_);
+  if (disconnected_) {
+    LOG(ERROR) << "Change processor disconnected.";
+    return false;
+  }
   DCHECK(has_nodes);
   DCHECK_NE(type, syncable::UNSPECIFIED);
   std::string type_name = syncable::ModelTypeToString(type);
@@ -236,6 +281,11 @@ bool GenericChangeProcessor::SyncModelHasUserCreatedNodes(
 }
 
 bool GenericChangeProcessor::CryptoReadyIfNecessary(syncable::ModelType type) {
+  AutoLock lock(monitor_lock_);
+  if (disconnected_) {
+    LOG(ERROR) << "Change processor disconnected.";
+    return true;  // Otherwise we get into infinite spin waiting.
+  }
   DCHECK_NE(type, syncable::UNSPECIFIED);
   // We only access the cryptographer while holding a transaction.
   sync_api::ReadTransaction trans(FROM_HERE, share_handle());
@@ -247,7 +297,9 @@ bool GenericChangeProcessor::CryptoReadyIfNecessary(syncable::ModelType type) {
 
 void GenericChangeProcessor::StartImpl(Profile* profile) {}
 
-void GenericChangeProcessor::StopImpl() {}
+void GenericChangeProcessor::StopImpl() {
+  Disconnect();
+}
 
 sync_api::UserShare* GenericChangeProcessor::share_handle() {
   return user_share_;