sandbox/win: Fix warnings found by clang chromium-style plugin on Windows.

sandbox/win/src/win2k_threadpool.h

Index: sandbox/win/src/win2k_threadpool.h
diff --git a/sandbox/win/src/win2k_threadpool.h b/sandbox/win/src/win2k_threadpool.h
index 0abb358e690959cc0e143372b67723f33386d7be..41cd5f13b711dd0539c367c3dcc007bf041ef846 100644
--- a/sandbox/win/src/win2k_threadpool.h
+++ b/sandbox/win/src/win2k_threadpool.h
@@ -24,9 +24,7 @@ namespace sandbox {
 // This implementation simply thunks to the nice thread pool API of win2k.
 class Win2kThreadPool : public ThreadProvider {
  public:
-  Win2kThreadPool() {
-    ::InitializeCriticalSection(&lock_);
-  }
+  Win2kThreadPool();
   virtual ~Win2kThreadPool();
 
   virtual bool RegisterWait(const void* cookie, HANDLE waitable_object,
@@ -50,6 +48,7 @@ class Win2kThreadPool : public ThreadProvider {
   PoolObjects pool_objects_;
   // This lock protects the list of pool wait objects.
   CRITICAL_SECTION lock_;
+
   DISALLOW_COPY_AND_ASSIGN(Win2kThreadPool);
 };