Prepare MediaDrmBridge to work with MediaCodecPlayer

media/cdm/player_tracker_impl.cc

Index: media/cdm/player_tracker_impl.cc
diff --git a/media/cdm/player_tracker_impl.cc b/media/cdm/player_tracker_impl.cc
index 8f102bd724e18ac00a200e2bfb4efd330b040131..e4abd61f707de3a6a2331cc21fdb342187b8df40 100644
--- a/media/cdm/player_tracker_impl.cc
+++ b/media/cdm/player_tracker_impl.cc
@@ -19,7 +19,11 @@ PlayerTrackerImpl::PlayerCallbacks::PlayerCallbacks(
 PlayerTrackerImpl::PlayerCallbacks::~PlayerCallbacks() {
 }
 
-PlayerTrackerImpl::PlayerTrackerImpl() : next_registration_id_(1) {}
+PlayerTrackerImpl::PlayerTrackerImpl() : next_registration_id_(1) {
+  // Enable PlayerTrackerImpl to be created on another thread than it will be
+  // later exclusively used.
+  thread_checker_.DetachFromThread();
+}
 
 PlayerTrackerImpl::~PlayerTrackerImpl() {}