sync: we can't lookup empty client tag nodes, so don't allow creating them

BUG=none
TEST=SyncApiTest.EmptyTags


Review URL: http://codereview.chromium.org/7970018

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@102432 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/sync/internal_api/syncapi_unittest.cc

@@ -564,6 +564,17 @@ TEST_F(SyncApiTest, BaseNodeGetDetailsAsValue) {
   }
 }
 
+TEST_F(SyncApiTest, EmptyTags) {
+  WriteTransaction trans(FROM_HERE, test_user_share_.user_share());
+  ReadNode root_node(&trans);
+  root_node.InitByRootLookup();
+  WriteNode node(&trans);
+  std::string empty_tag;
+  EXPECT_FALSE(node.InitUniqueByCreation(
+      syncable::TYPED_URLS, root_node, empty_tag));
+  EXPECT_FALSE(node.InitByTagLookup(empty_tag));
+}
+
 namespace {
 
 class TestHttpPostProviderInterface : public HttpPostProviderInterface {

chrome/browser/sync/internal_api/write_node.cc

@@ -394,6 +394,10 @@ bool WriteNode::InitUniqueByCreation(syncable::ModelType model_type,
                                      const BaseNode& parent,
                                      const std::string& tag) {
   DCHECK(!entry_) << "Init called twice";
+  if (tag.empty()) {
+    LOG(WARNING) << "InitUniqueByCreation failed due to empty tag.";
+    return false;
+  }
 
   const std::string hash = GenerateSyncableHash(model_type, tag);