Fixes compile error

build/precompile.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Precompiled header for Chromium project on Windows, not used by
 // other build configurations. Using precompiled headers speeds the
 // build up significantly, around 1/4th on VS 2010 on an HP Z600 with 12
 // GB of memory.
 //
 // Numeric comments beside includes are the number of times they were
 // included under src/chrome/browser on 2011/8/20, which was used as a
 // baseline for deciding what to include in the PCH. Includes without
 // a numeric comment are generally included at least 5 times. It may
 // be possible to tweak the speed of the build by commenting out or
 // removing some of the less frequently used headers.
 
 #if defined(BUILD_PRECOMPILE_H_)
 #error You shouldn't include the precompiled header file more than once.
 #endif
 
 #define BUILD_PRECOMPILE_H_
 
+#define _USE_MATH_DEFINES
+
 // The Windows header needs to come before almost all the other
 // Windows-specific headers.
 #include <Windows.h>
 #include <dwmapi.h>
 #include <shellapi.h>
 #include <wincrypt.h>  // 4
 #include <wtypes.h>  // 2
 
 // Defines in atlbase.h cause conflicts; if we could figure out how
 // this family of headers can be included in the PCH, it might speed
@@ skipping 66 matching lines @@
 #include <map>
 #include <numeric>  // 2
 #include <ostream>
 #include <queue>
 #include <set>
 #include <sstream>
 #include <stack>
 #include <string>
 #include <utility>
 #include <vector>