Fix VS 2015 warning by adding an additional cast

webrtc/base/criticalsection.cc

 /*
  *  Copyright 2015 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 70 matching lines @@
   RTC_DCHECK(recursion_count_ >= 0);
   if (!recursion_count_)
     thread_ = 0;
 #endif
   pthread_mutex_unlock(&mutex_);
 #endif
 }
 
 bool CriticalSection::CurrentThreadIsOwner() const {
 #if defined(WEBRTC_WIN)
-  return crit_.OwningThread == reinterpret_cast<HANDLE>(GetCurrentThreadId());
+  // OwningThread has type HANDLE but actually contains the Thread ID:
+  // http://stackoverflow.com/questions/12675301/why-is-the-owningthread-member-of-critical-section-of-type-handle-when-it-is-de
+  // Converting through size_t avoids the VS 2015 warning C4312: conversion from
+  // 'type1' to 'type2' of greater size
+  return crit_.OwningThread ==
+         reinterpret_cast<HANDLE>(static_cast<size_t>(GetCurrentThreadId()));
 #else
 #if CS_DEBUG_CHECKS
   return pthread_equal(thread_, pthread_self());
 #else
   return true;
 #endif  // CS_DEBUG_CHECKS
 #endif
 }
 
 bool CriticalSection::IsLocked() const {
@@ skipping 53 matching lines @@
 GlobalLockScope::GlobalLockScope(GlobalLockPod* lock)
     : lock_(lock) {
   lock_->Lock();
 }
 
 GlobalLockScope::~GlobalLockScope() {
   lock_->Unlock();
 }
 
 }  // namespace rtc