Add Isolate::DiscardThreadSpecificMetadata method to embedder API.

src/isolate.cc

Index: src/isolate.cc
diff --git a/src/isolate.cc b/src/isolate.cc
index 927989f367f053979a87e6c357433581e1074a0d..77611c782e2f0dde7e4d0cf84ab976b50c6c9dec 100644
--- a/src/isolate.cc
+++ b/src/isolate.cc
@@ -135,6 +135,22 @@ Isolate::PerIsolateThreadData*
 }
 
 
+void Isolate::DiscardPerThreadDataForThisThread() {
+  int thread_id_int = base::Thread::GetThreadLocalInt(Isolate::thread_id_key_);
+  if (thread_id_int) {
+    ThreadId thread_id = ThreadId(thread_id_int);
+    DCHECK(!thread_manager_->mutex_owner_.Equals(thread_id));
+    base::LockGuard<base::Mutex> lock_guard(thread_data_table_mutex_.Pointer());
+    PerIsolateThreadData* per_thread =
+        thread_data_table_->Lookup(this, thread_id);
+    if (per_thread) {
+      DCHECK(!per_thread->thread_state_);
+      thread_data_table_->Remove(per_thread);
+    }
+  }
+}
+
+
 Isolate::PerIsolateThreadData* Isolate::FindPerThreadDataForThisThread() {
   ThreadId thread_id = ThreadId::Current();
   return FindPerThreadDataForThread(thread_id);