[Sync] InvalidationService shouldn't CHECK when registering ObjectId for more than one handler

chrome/browser/policy/cloud/cloud_policy_invalidator.cc

Index: chrome/browser/policy/cloud/cloud_policy_invalidator.cc
diff --git a/chrome/browser/policy/cloud/cloud_policy_invalidator.cc b/chrome/browser/policy/cloud/cloud_policy_invalidator.cc
index c197f978203fb85fa1fb394f5f001a214118ed55..02bd109b854e86e9899443e8720ebc531793494b 100644
--- a/chrome/browser/policy/cloud/cloud_policy_invalidator.cc
+++ b/chrome/browser/policy/cloud/cloud_policy_invalidator.cc
@@ -308,16 +308,15 @@ void CloudPolicyInvalidator::Register(const invalidation::ObjectId& object_id) {
   // Update registration with the invalidation service.
   syncer::ObjectIdSet ids;
   ids.insert(object_id);
-  invalidation_service_->UpdateRegisteredInvalidationIds(this, ids);
+  CHECK(invalidation_service_->UpdateRegisteredInvalidationIds(this, ids));

[bartfab (slow), 2015/05/19 10:44:42]

Nit 1: #include "base/logging.h"
Nit 2: I think a LOG(ERROR) is more appropriate than a CHECK(). If we receive
invalid data from the cloud, invalidation will not work - no need to crash the
whole browser because of that.

[pavely, 2015/05/19 17:54:55]

#1: Done

#2: I wanted this change to preserve existing behavior, but allow call sites to
do something smarter than just crash. LOG(ERROR) would work but would not allow
us to see issues: invalid data would cause degraded experience and we'll never
find out about it.
You proposed earlier to report UMA histogram in such situations, this is the
place to do it. Let's land this change as it is and you'll add appropriate
reaction.

 }
 
 void CloudPolicyInvalidator::Unregister() {
   if (is_registered_) {
     if (invalid_)
       AcknowledgeInvalidation();
-    invalidation_service_->UpdateRegisteredInvalidationIds(
-        this,
-        syncer::ObjectIdSet());
+    CHECK(invalidation_service_->UpdateRegisteredInvalidationIds(
+        this, syncer::ObjectIdSet()));
     invalidation_service_->UnregisterInvalidationHandler(this);
     is_registered_ = false;
     UpdateInvalidationsEnabled();