[Sync] Add plumbing of context from client to server

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 d2204eb70edbc5a52ddb332f5c2fb5598b80c787..194a5b4c57c158e92ecb47dd25e35e10eb762726 100644
--- a/chrome/browser/sync/glue/generic_change_processor.cc
+++ b/chrome/browser/sync/glue/generic_change_processor.cc
@@ -18,6 +18,7 @@
 #include "sync/internal_api/public/util/unrecoverable_error_handler.h"
 #include "sync/internal_api/public/write_node.h"
 #include "sync/internal_api/public/write_transaction.h"
+#include "sync/syncable/directory.h"
 #include "sync/syncable/entry.h"  // TODO(tim): Bug 123674.
 
 using content::BrowserThread;
@@ -153,7 +154,21 @@ syncer::SyncDataList GenericChangeProcessor::GetAllSyncData(
 syncer::SyncError GenericChangeProcessor::UpdateDataTypeContext(
     syncer::ModelType type,
     const std::string& context) {
-  NOTIMPLEMENTED();
+  syncer::WriteTransaction trans(FROM_HERE, share_handle());
+  sync_pb::DataTypeContext context_proto;
+  trans.GetDirectory()->GetDataTypeContext(type, &context_proto);
+
+  if (context_proto.context() == context)
+    return syncer::SyncError();  // Context already matches.

[rlarocque, 2014/04/03 17:31:58]

Why is this an error?  It seems harmless.

[Nicolas Zea, 2014/04/03 22:56:47]

default-initialized SyncError aren't errors.

+
+  if (context_proto.type() == 0)
+    context_proto.set_type(syncer::GetSpecificsFieldNumberFromModelType(type));
+  DCHECK_EQ(syncer::GetSpecificsFieldNumberFromModelType(type),
+            context_proto.type());
+  DCHECK_GE(context_proto.version(), 0);
+  context_proto.set_version(context_proto.version() + 1);
+  context_proto.set_context(context);
+  trans.GetDirectory()->SetDataTypeContext(type, context_proto);
   return syncer::SyncError();
 }