[Sync] Add support for performing a GetKey on startup.

sync/engine/download_updates_command.cc

Index: sync/engine/download_updates_command.cc
diff --git a/sync/engine/download_updates_command.cc b/sync/engine/download_updates_command.cc
index 22839f60d0ba3798e8e7bf695d0b71e15c4b6440..8a3078541a9aedaba7914fc099121382d17f2503 100644
--- a/sync/engine/download_updates_command.cc
+++ b/sync/engine/download_updates_command.cc
@@ -11,6 +11,7 @@
 #include "sync/engine/syncer_proto_util.h"
 #include "sync/internal_api/public/base/model_type_payload_map.h"
 #include "sync/syncable/directory.h"
+#include "sync/syncable/read_transaction.h"
 
 using sync_pb::DebugInfo;
 
@@ -62,6 +63,17 @@ SyncerError DownloadUpdatesCommand::ExecuteImpl(SyncSession* session) {
     }
   }
 
+  bool need_encryption_key = false;
+  if (session->context()->keystore_encryption_enabled()) {
+    syncable::Directory* dir = session->context()->directory();
+    syncable::ReadTransaction trans(FROM_HERE, dir);
+    Cryptographer* cryptographer =
+        session->context()->directory()->GetCryptographer(&trans);
+    need_encryption_key = !cryptographer->HasKeystoreKey();
+    get_updates->set_need_encryption_key(need_encryption_key);
+
+  }
+
   // We want folders for our associated types, always.  If we were to set
   // this to false, the server would send just the non-container items
   // (e.g. Bookmark URLs but not their containing folders).
@@ -103,6 +115,28 @@ SyncerError DownloadUpdatesCommand::ExecuteImpl(SyncSession* session) {
            << " updates and indicated "
            << update_response.get_updates().changes_remaining()
            << " updates left on server.";
+
+  if (need_encryption_key) {

[tim (not reviewing), 2012/07/26 21:53:15]

Can you put this into a helper method for sake of readability?  

[Nicolas Zea, 2012/07/27 00:43:15]

Done.

+    bool success = false;
+    if (update_response.get_updates().has_encryption_key()) {
+      syncable::Directory* dir = session->context()->directory();
+      syncable::ReadTransaction trans(FROM_HERE, dir);
+      Cryptographer* cryptographer =
+          session->context()->directory()->GetCryptographer(&trans);
+      success = cryptographer->SetKeystoreKey(
+          update_response.get_updates().encryption_key());
+
+      DVLOG(1) << "GetUpdates returned encryption key of length "
+               << update_response.get_updates().encryption_key().length()
+               << ". Cryptographer keystore key "
+               << (success ? "" : "not ") << "updated.";
+    } else {
+      LOG(ERROR) << "Failed to receive encryption key from server.";
+    }
+    status->set_last_get_key_result(
+        success ? SYNCER_OK : SERVER_RESPONSE_VALIDATION_FAILED);
+  }
+
   return result;
 }