Adding DCHECKs and constness to DtlsIdentityStore.

talk/app/webrtc/dtlsidentitystore.cc

Index: talk/app/webrtc/dtlsidentitystore.cc
diff --git a/talk/app/webrtc/dtlsidentitystore.cc b/talk/app/webrtc/dtlsidentitystore.cc
index dd9bc5d68b501898b1ceada01b7555232953e48e..945429a67125592cf868e88bdb966bf014e3ac57 100644
--- a/talk/app/webrtc/dtlsidentitystore.cc
+++ b/talk/app/webrtc/dtlsidentitystore.cc
@@ -116,6 +116,7 @@ DtlsIdentityStore::~DtlsIdentityStore() {
 }
 
 void DtlsIdentityStore::Initialize() {
+  DCHECK(rtc::Thread::Current() == signaling_thread_);
   // Do not aggressively generate the free identity if the worker thread and the
   // signaling thread are the same.
   if (worker_thread_ != signaling_thread_) {
@@ -156,10 +157,12 @@ void DtlsIdentityStore::OnMessage(rtc::Message* msg) {
 }
 
 bool DtlsIdentityStore::HasFreeIdentityForTesting() const {
-  return free_identity_.get();
+  DCHECK(rtc::Thread::Current() == signaling_thread_);
+  return free_identity_.get() != nullptr;
 }
 
 void DtlsIdentityStore::GenerateIdentity() {

[hbos, 2015/06/09 12:59:11]

It's confusing that we have two GenerateIdentity in the same file, and figuring
out what is going on requires staring at the code for a bit. Can we rename one
of them for clarity?

Perhaps this can be called StartGenerateIdentityOnWorkerThread() if that's not
too long of a name. Or with a less descriptive name perhaps add a comment.

[tommi, 2015/06/09 13:17:17]

I added the _w() post fix to the one that runs on the worker thread.  That seems
to be the convention in this file.  Also made most methods of WorkerTask
private.

+  DCHECK(rtc::Thread::Current() == signaling_thread_);
   pending_jobs_++;
   LOG(LS_VERBOSE) << "New DTLS identity generation is posted, "
                   << "pending_identities=" << pending_jobs_;
@@ -191,6 +194,7 @@ void DtlsIdentityStore::OnIdentityGenerated(
 
 void DtlsIdentityStore::ReturnIdentity(
     rtc::scoped_ptr<rtc::SSLIdentity> identity) {
+  DCHECK(rtc::Thread::Current() == signaling_thread_);
   DCHECK(!free_identity_.get());
   DCHECK(!pending_observers_.empty());
 
@@ -211,8 +215,8 @@ void DtlsIdentityStore::ReturnIdentity(
   if (worker_thread_ != signaling_thread_ &&
       pending_observers_.empty() &&
       pending_jobs_ == 0) {
-      // Generate a free identity in the background.
-      GenerateIdentity();
+    // Generate a free identity in the background.
+    GenerateIdentity();

[hbos, 2015/06/09 12:59:12]

(This generates in case we want to request another identity in the future,
right?)

[tommi, 2015/06/09 13:17:17]

yes.  I guess that's what the "free identity" reference in the comment refers
to.

   }
 }