media: Make MediaKeys ref-counted.

chromecast/media/cdm/browser_cdm_cast.cc

Index: chromecast/media/cdm/browser_cdm_cast.cc
diff --git a/chromecast/media/cdm/browser_cdm_cast.cc b/chromecast/media/cdm/browser_cdm_cast.cc
index fa4195ad3c9cafb55bda1672a0c2a1af860e0b08..c864930e70af0e5ff97f2ee4cfcf1c3fdeef4c0c 100644
--- a/chromecast/media/cdm/browser_cdm_cast.cc
+++ b/chromecast/media/cdm/browser_cdm_cast.cc
@@ -89,7 +89,7 @@ void BrowserCdmCast::Initialize(
     const ::media::SessionExpirationUpdateCB& session_expiration_update_cb) {
   DCHECK(thread_checker_.CalledOnValidThread());
 
-  player_tracker_impl_.reset(new ::media::PlayerTrackerImpl);
+  player_tracker_impl_.reset(new ::media::PlayerTrackerImpl());
 
   session_message_cb_ = session_message_cb;
   session_closed_cb_ = session_closed_cb;
@@ -154,24 +154,13 @@ void BrowserCdmCast::OnSessionKeysChange(
                  base::Unretained(browser_cdm_cast_.get()), ##__VA_ARGS__))
 
 BrowserCdmCastUi::BrowserCdmCastUi(
-    scoped_ptr<BrowserCdmCast> browser_cdm_cast,
+    const scoped_refptr<BrowserCdmCast>& browser_cdm_cast,
     const scoped_refptr<base::SingleThreadTaskRunner>& task_runner)
-    : browser_cdm_cast_(browser_cdm_cast.Pass()), task_runner_(task_runner) {
-}
+    : browser_cdm_cast_(browser_cdm_cast), task_runner_(task_runner) {}
 
 BrowserCdmCastUi::~BrowserCdmCastUi() {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  task_runner_->DeleteSoon(FROM_HERE, browser_cdm_cast_.release());
-}
-
-int BrowserCdmCastUi::RegisterPlayer(const base::Closure& new_key_cb,
-                                     const base::Closure& cdm_unset_cb) {
-  NOTREACHED() << "RegisterPlayer should be called on BrowserCdmCast";
-  return -1;
-}
-
-void BrowserCdmCastUi::UnregisterPlayer(int registration_id) {
-  NOTREACHED() << "UnregisterPlayer should be called on BrowserCdmCast";
+  // |this| should be destroyed on |task_runner_|.
+  DCHECK(task_runner_->BelongsToCurrentThread());

[gunsch, 2015/10/28 20:51:01]

It seems a little awkward to toss out thread_checker_ here and be okay with
destroying this class on another thread than all of its calls come in on. It
might not be an issue in practice (since BrowserCdmCastUi doesn't hold any
interesting members except for BrowserCdmCast).

Is there a reason to prefer this to simply releasing the browser_cdm_cast_
reference on the CDM thread, keeping closer behavior to before?

[xhwang, 2015/10/29 00:17:28]

As discussed offline (thanks!), using ReleaseSoon with the Addref/raw-pointer
magic.

 }
 
 BrowserCdmCast* BrowserCdmCastUi::browser_cdm_cast() const {
@@ -246,6 +235,11 @@ void BrowserCdmCastUi::RemoveSession(
   return nullptr;
 }
 
+void BrowserCdmCastUi::DeleteOnCorrectThread() const {
+  // Always destroy |this| on |task_runner_|.
+  task_runner_->DeleteSoon(FROM_HERE, this);
+}
+
 // A default empty implementation for subclasses that don't need to provide
 // any key system specific initialization.
 void BrowserCdmCast::InitializeInternal() {