Add CHECKs to ensure that PPAPI resources are created on the right thread

ppapi/shared_impl/resource_tracker.cc

Index: ppapi/shared_impl/resource_tracker.cc
diff --git a/ppapi/shared_impl/resource_tracker.cc b/ppapi/shared_impl/resource_tracker.cc
index 8cfcfb52c35c387cc5fe758535b6afaf528fcd6d..da897743528490ac49949cf66dc357762a4630f8 100644
--- a/ppapi/shared_impl/resource_tracker.cc
+++ b/ppapi/shared_impl/resource_tracker.cc
@@ -23,6 +23,7 @@ ResourceTracker::~ResourceTracker() {
 }
 
 Resource* ResourceTracker::GetResource(PP_Resource res) const {
+  CHECK(thread_checker_.CalledOnValidThread());
   ResourceMap::const_iterator i = live_resources_.find(res);
   if (i == live_resources_.end())
     return NULL;
@@ -30,6 +31,7 @@ Resource* ResourceTracker::GetResource(PP_Resource res) const {
 }
 
 void ResourceTracker::AddRefResource(PP_Resource res) {
+  CHECK(thread_checker_.CalledOnValidThread());
   DLOG_IF(ERROR, !CheckIdType(res, PP_ID_TYPE_RESOURCE))
       << res << " is not a PP_Resource.";
   ResourceMap::iterator i = live_resources_.find(res);
@@ -51,6 +53,7 @@ void ResourceTracker::AddRefResource(PP_Resource res) {
 }
 
 void ResourceTracker::ReleaseResource(PP_Resource res) {
+  CHECK(thread_checker_.CalledOnValidThread());
   DLOG_IF(ERROR, !CheckIdType(res, PP_ID_TYPE_RESOURCE))
       << res << " is not a PP_Resource.";
   ResourceMap::iterator i = live_resources_.find(res);
@@ -81,6 +84,7 @@ void ResourceTracker::ReleaseResourceSoon(PP_Resource res) {
 }
 
 void ResourceTracker::DidCreateInstance(PP_Instance instance) {
+  CHECK(thread_checker_.CalledOnValidThread());
   // Due to the infrastructure of some tests, the instance is registered
   // twice in a few cases. It would be nice not to do that and assert here
   // instead.
@@ -90,6 +94,7 @@ void ResourceTracker::DidCreateInstance(PP_Instance instance) {
 }
 
 void ResourceTracker::DidDeleteInstance(PP_Instance instance) {
+  CHECK(thread_checker_.CalledOnValidThread());
   InstanceMap::iterator found_instance = instance_map_.find(instance);
 
   // Due to the infrastructure of some tests, the instance is unregistered
@@ -144,6 +149,7 @@ void ResourceTracker::DidDeleteInstance(PP_Instance instance) {
 }
 
 int ResourceTracker::GetLiveObjectsForInstance(PP_Instance instance) const {
+  CHECK(thread_checker_.CalledOnValidThread());
   InstanceMap::const_iterator found = instance_map_.find(instance);
   if (found == instance_map_.end())
     return 0;
@@ -151,6 +157,7 @@ int ResourceTracker::GetLiveObjectsForInstance(PP_Instance instance) const {
 }
 
 PP_Resource ResourceTracker::AddResource(Resource* object) {
+  CHECK(thread_checker_.CalledOnValidThread());
   // If the plugin manages to create too many resources, don't do crazy stuff.
   if (last_resource_value_ == kMaxPPId)
     return 0;
@@ -182,6 +189,7 @@ PP_Resource ResourceTracker::AddResource(Resource* object) {
 }
 
 void ResourceTracker::RemoveResource(Resource* object) {
+  CHECK(thread_checker_.CalledOnValidThread());
   PP_Resource pp_resource = object->pp_resource();
   InstanceMap::iterator found = instance_map_.find(object->pp_instance());
   if (found != instance_map_.end())