Move the COMPILE_ASSERT macro to its own header file.

TEST=n/a
BUG=none
Review URL: https://webrtc-codereview.appspot.com/492002

git-svn-id: http://webrtc.googlecode.com/svn/trunk@2001 4adac7df-926f-26a2-2b94-8c16560cd09d

src/modules/rtp_rtcp/source/rtp_format_vp8_unittest.cc

@@ -1,5 +1,5 @@
 /*
- *  Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
+ *  Copyright (c) 2012 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
@@ -15,20 +15,14 @@
 
 #include <gtest/gtest.h>
 
+#include "compile_assert.h"
+
 #include "modules/rtp_rtcp/source/rtp_format_vp8.h"
 #include "modules/rtp_rtcp/source/rtp_format_vp8_test_helper.h"
 #include "typedefs.h"
 
 namespace webrtc {
 
-template <bool>
-struct CompileAssert {
-};
-
-#undef COMPILE_ASSERT
-#define COMPILE_ASSERT(expr, msg) \
-  typedef CompileAssert<(bool(expr))> msg[bool(expr) ? 1 : -1]
-
 class RtpFormatVp8Test : public ::testing::Test {
  protected:
   RtpFormatVp8Test() : helper_(NULL) {}

src/system_wrappers/interface/compile_assert.h

@@ -0,0 +1,27 @@
+/*
+ *  Copyright (c) 2012 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.
+ */
+
+#ifndef WEBRTC_SYSTEM_WRAPPERS_INTERFACE_COMPILE_ASSERT_H_
+#define WEBRTC_SYSTEM_WRAPPERS_INTERFACE_COMPILE_ASSERT_H_
+
+template <bool>
+struct CompileAssert {};
+
+// Use this macro to verify at compile time that certain restrictions are met.
+// The first argument is the expression to evaluate, the second is a unique
+// identifier for the assert.
+// Example:
+//   COMPILE_ASSERT(sizeof(foo) < 128, foo_too_large);
+#undef COMPILE_ASSERT
+#define COMPILE_ASSERT(expr, msg) \
+    typedef CompileAssert<static_cast<bool>(expr)> \
+        msg[static_cast<bool>(expr) ? 1 : -1]
+
+#endif  // WEBRTC_SYSTEM_WRAPPERS_INTERFACE_COMPILE_ASSERT_H_

src/system_wrappers/source/system_wrappers.gyp

@@ -24,6 +24,7 @@
       'sources': [
         '../interface/aligned_malloc.h',
         '../interface/atomic32_wrapper.h',
+        '../interface/compile_assert.h',
         '../interface/condition_variable_wrapper.h',
         '../interface/cpu_info.h',
         '../interface/cpu_wrapper.h',