[Sync] Add plumbing of context from client to server

The datatype context is now written into the directory and plumbed up to the
server on every GetUpdates or Commit request. GetUpdatesResponses also now
overwrite the context if the version returned is the same or higher.

BUG=345420

Review URL: https://codereview.chromium.org/215973007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@261873 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 12 insertions, 3 deletions

diff --git a/sync/test/engine/mock_update_handler.cc b/sync/test/engine/mock_update_handler.cc
index 098086e..da2db88 100644
--- a/sync/test/engine/mock_update_handler.cc
+++ b/sync/test/engine/mock_update_handler.cc
@@ -24,10 +24,16 @@ void MockUpdateHandler::GetDownloadProgress(
   progress_marker->CopyFrom(progress_marker_);
 }
 
+void MockUpdateHandler::GetDataTypeContext(
+    sync_pb::DataTypeContext* context) const {
+  context->Clear();
+}
+
 void MockUpdateHandler::ProcessGetUpdatesResponse(
-      const sync_pb::DataTypeProgressMarker& progress_marker,
-      const SyncEntityList& applicable_updates,
-      sessions::StatusController* status) {
+    const sync_pb::DataTypeProgressMarker& progress_marker,
+    const sync_pb::DataTypeContext& mutated_context,
+    const SyncEntityList& applicable_updates,
+    sessions::StatusController* status) {
   progress_marker_.CopyFrom(progress_marker);
 }
 
diff --git a/sync/test/engine/mock_update_handler.h b/sync/test/engine/mock_update_handler.h
index 8d11f96..0cbeca3 100644
--- a/sync/test/engine/mock_update_handler.h
+++ b/sync/test/engine/mock_update_handler.h
@@ -20,8 +20,11 @@ class MockUpdateHandler : public UpdateHandler {
   // UpdateHandler implementation.
   virtual void GetDownloadProgress(
       sync_pb::DataTypeProgressMarker* progress_marker) const OVERRIDE;
+  virtual void GetDataTypeContext(sync_pb::DataTypeContext* context) const
+      OVERRIDE;
   virtual void ProcessGetUpdatesResponse(
       const sync_pb::DataTypeProgressMarker& progress_marker,
+      const sync_pb::DataTypeContext& mutated_context,
       const SyncEntityList& applicable_updates,
       sessions::StatusController* status) OVERRIDE;
   virtual void ApplyUpdates(sessions::StatusController* status) OVERRIDE;