Move libplatform files into v8::platform namespace

src/libplatform/worker-thread.h

Index: src/libplatform/worker-thread.h
diff --git a/src/libplatform/worker-thread.h b/src/libplatform/worker-thread.h
index 5942b93660a2633b7b057af414075ad22b866611..5550f16a7f69a2817dbeb21661ea156f5e456eb2 100644
--- a/src/libplatform/worker-thread.h
+++ b/src/libplatform/worker-thread.h
@@ -12,7 +12,7 @@
 
 namespace v8 {
 
-namespace internal {
+namespace platform {
 
 class TaskQueue;
 
@@ -32,7 +32,7 @@ class WorkerThread : public base::Thread {
   DISALLOW_COPY_AND_ASSIGN(WorkerThread);
 };
 
-} }  // namespace v8::internal
+} }  // namespace v8::platform
 
 
 #endif  // V8_LIBPLATFORM_WORKER_THREAD_H_