Move platform_thread to base/threading and put in the base namespace. I left a
stub and "using" declarations in the old location to avoid having to change the
entire project at once.

TEST=it compiles
BUG=none
Review URL: http://codereview.chromium.org/6001010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@70342 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/base/threading/worker_pool_posix.cc b/base/threading/worker_pool_posix.cc
index 2facc01..84664037 100644
--- a/base/threading/worker_pool_posix.cc
+++ b/base/threading/worker_pool_posix.cc
@@ -6,10 +6,10 @@
 
 #include "base/lazy_instance.h"
 #include "base/logging.h"
-#include "base/platform_thread.h"
 #include "base/ref_counted.h"
 #include "base/stringprintf.h"
 #include "base/task.h"
+#include "base/threading/platform_thread.h"
 #include "base/threading/worker_pool.h"
 
 namespace base {