Explode Autofill sync error messages for debugging

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 3317c89cfe2d6d5c4b1de96b03e7540977fd3d29..9ca09f7207619aa77a4258bae77721ce150fcbca 100644
--- a/chrome/browser/sync/glue/generic_change_processor.cc
+++ b/chrome/browser/sync/glue/generic_change_processor.cc
@@ -128,26 +128,58 @@ SyncError GenericChangeProcessor::GetSyncDataForType(
 
 namespace {
 
-bool AttemptDelete(const SyncChange& change, sync_api::WriteNode* node) {
+// TODO(isherman): Investigating http://crbug.com/121592
+std::string GetErrorExplanation(sync_api::BaseNode::InitByLookupResult result) {
+  switch (result) {
+    case sync_api::BaseNode::INIT_FAILED_ENTRY_NOT_GOOD:
+      return " could not find entry matching the lookup criteria.";
+    case sync_api::BaseNode::INIT_FAILED_ENTRY_IS_DEL:
+      return " entry is already deleted.";
+    case sync_api::BaseNode::INIT_FAILED_DECRYPT_IF_NECESSARY:
+      return " unable to decrypt.";
+    case sync_api::BaseNode::INIT_FAILED_PRECONDITION:
+      return " a precondition was not met for calling init.";
+    default:
+      // Should have listed all the possible error cases above.
+      NOTREACHED();
+      return "";
+  }
+}
+
+SyncError AttemptDelete(const SyncChange& change,
+                        syncable::ModelType type,
+                        std::string type_str,
+                        sync_api::WriteNode* node) {
   DCHECK_EQ(change.change_type(), SyncChange::ACTION_DELETE);
   if (change.sync_data().IsLocal()) {
     const std::string& tag = change.sync_data().GetTag();
     if (tag.empty()) {
-      return false;
+      return SyncError(
+          FROM_HERE,
+          "Failed to delete " + type_str + " node. Local data, empty tag.",
+          type);
     }
-    if (node->InitByClientTagLookup(
-            change.sync_data().GetDataType(), tag) !=
-            sync_api::BaseNode::INIT_OK) {
-      return false;
+
+    sync_api::BaseNode::InitByLookupResult result =
+        node->InitByClientTagLookup(change.sync_data().GetDataType(), tag);
+    if (result != sync_api::BaseNode::INIT_OK) {
+      return SyncError(FROM_HERE,
+                       "Failed to delete " + type_str + " node. "
+                           "Local data, " + GetErrorExplanation(result),
+                       type);
     }
   } else {
-    if (node->InitByIdLookup(change.sync_data().GetRemoteId()) !=
-            sync_api::BaseNode::INIT_OK) {
-      return false;
+    sync_api::BaseNode::InitByLookupResult result =
+        node->InitByIdLookup(change.sync_data().GetRemoteId());
+    if (result != sync_api::BaseNode::INIT_OK) {
+      return SyncError(FROM_HERE,
+                       "Failed to delete " + type_str + " node. "
+                           "Non-local data, " + GetErrorExplanation(result),
+                       type);
     }
   }
   node->Remove();
-  return true;
+  return SyncError();
 }
 
 }  // namespace
@@ -167,11 +199,9 @@ SyncError GenericChangeProcessor::ProcessSyncChanges(
     std::string type_str = syncable::ModelTypeToString(type);
     sync_api::WriteNode sync_node(&trans);
     if (change.change_type() == SyncChange::ACTION_DELETE) {
-      if (!AttemptDelete(change, &sync_node)) {
+      SyncError error = AttemptDelete(change, type, type_str, &sync_node);

[tim (not reviewing), 2012/05/15 16:44:12]

This still doesn't quite do it :P Think of OnSingleDataTypeUnrecoverableError as
a CHECK statement.  The location parameter is only used for local logging; what
matters is the actual line of code that OnSingleDatatypeUnrecoverableError is
itself called on.

[Ilya Sherman, 2012/05/16 00:43:06]

*sigh* ok, new patch set up... lots of repeated code, but if that's what it
takes, so be it :)

+      if (error.IsSet()) {
         NOTREACHED();
-        SyncError error(FROM_HERE,
-                        "Failed to delete " + type_str + " node.",
-                        type);
         error_handler()->OnSingleDatatypeUnrecoverableError(error.location(),
                                                             error.message());
         return error;