Precompile out our standalone CHECK macros in a Chromium build.

As documented, the use of overrides/webrtc/base/logging.h in a Chromium
build reuslts in redefined macro errors. Fortunately, Chromium's macros
can be used as drop-in replacements for the standalone versions.

TBR=henrike

Review URL: https://webrtc-codereview.appspot.com/17239004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@7004 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/base/checks.cc

@@ -111,6 +111,9 @@ void FatalMessage::Init(const char* file, int line) {
           << file << ", line " << line << std::endl << "# ";
 }
 
+// Refer to comments in checks.h.
+#ifndef WEBRTC_CHROMIUM_BUILD
+
 // MSVC doesn't like complex extern templates and DLLs.
 #if !defined(COMPILER_MSVC)
 // Explicit instantiations for commonly used comparisons.
@@ -126,4 +129,6 @@ template std::string* MakeCheckOpString<std::string, std::string>(
     const std::string&, const std::string&, const char* name);
 #endif
 
+#endif  // WEBRTC_CHROMIUM_BUILD
+
 }  // namespace rtc

webrtc/base/checks.h

@@ -52,6 +52,11 @@
 
 namespace rtc {
 
+// The use of overrides/webrtc/base/logging.h in a Chromium build results in
+// redefined macro errors. Fortunately, Chromium's macros can be used as drop-in
+// replacements for the standalone versions.
+#ifndef WEBRTC_CHROMIUM_BUILD
+
 // Helper macro which avoids evaluating the arguments to a stream if
 // the condition doesn't hold.
 #define LAZY_STREAM(stream, condition)                          \
@@ -162,6 +167,8 @@ DEFINE_CHECK_OP_IMPL(GT, > )
 #define DCHECK_LE(v1, v2) EAT_STREAM_PARAMETERS
 #endif
 
+#endif  // WEBRTC_CHROMIUM_BUILD
+
 #define FATAL() rtc::FatalMessage(__FILE__, __LINE__).stream()
 // TODO(ajm): Consider adding NOTIMPLEMENTED and NOTREACHED macros when
 // base/logging.h and system_wrappers/logging.h are consolidated such that we