Ensure we never try to register for the object id "NULL"

sync/android/java/src/org/chromium/sync/notifier/InvalidationService.java

Index: sync/android/java/src/org/chromium/sync/notifier/InvalidationService.java
diff --git a/sync/android/java/src/org/chromium/sync/notifier/InvalidationService.java b/sync/android/java/src/org/chromium/sync/notifier/InvalidationService.java
index 92ac257bc703fed16bd300c08462040643cb0ffe..c9f351f8937a71bf8743096c26b0bb65a8be8679 100644
--- a/sync/android/java/src/org/chromium/sync/notifier/InvalidationService.java
+++ b/sync/android/java/src/org/chromium/sync/notifier/InvalidationService.java
@@ -296,6 +296,7 @@ public class InvalidationService extends AndroidListener {
             return Collections.emptySet();
         } else {
             Set<ModelType> modelTypes = ModelType.syncTypesToModelTypes(savedTypes);
+            modelTypes = ModelType.stripNonInvalidationTypes(modelTypes);
             Set<ObjectId> objectIds = Sets.newHashSetWithExpectedSize(modelTypes.size());

[Yaron, 2013/08/08 01:52:16]

These 4 lines can be replaced with ModelType.modelTypesToObjectIds.
That said we're now iterating through all types 3 times, creating copies each
time (or maybe twice depending on other comment). Seems suboptimal.

Also, is it too weird to just do this in modelTypesToObjectIds? You'd never want
the null type there, so you could strip it at conversion time and leave sync
types alone.

[nyquist, 2013/08/08 17:59:28]

Simplified this, and moved logic to modelTypesToObjectIds.
Still iterates twice though, but code is still fairly easy to read.

The manual call to toObjectId seems to only be used in tests, so added an
explanatory comment that it should be used with caution.

             for (ModelType modelType : modelTypes) {
                 objectIds.add(modelType.toObjectId());
@@ -338,6 +339,8 @@ public class InvalidationService extends AndroidListener {
         // NOTE: syncTypes MUST NOT be used below this line, since it contains an unexpanded
         // wildcard.
         Set<ModelType> newRegisteredTypes = ModelType.syncTypesToModelTypes(syncTypes);
+        // Some types should never receive notifications.
+        newRegisteredTypes = ModelType.stripNonInvalidationTypes(newRegisteredTypes);
 
         List<ObjectId> unregistrations = Lists.newArrayList();
         List<ObjectId> registrations = Lists.newArrayList();