Fix "defined but not used" warning in base/message_loop/message_loop.cc

PNaCl is being upgraded to Clang 3.4, which now warns about unused
declarations inside anonymous namespaces.

BUG=https://code.google.com/p/nativeclient/issues/detail?id=3757
TEST=compile using new PNaCl toolchain
R=darin@chromium.org, thakis@chromium.org

Review URL: https://codereview.chromium.org/185583002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@254690 0039d316-1c4b-4281-b951-d872f2087c98


CrOS-Libchrome-Original-Commit: 19e273c317cee4a2952da8687b569ad7083d0c98
diff --git a/base/message_loop/message_loop.cc b/base/message_loop/message_loop.cc
index 8f6c9d8..e14ce85 100644
--- a/base/message_loop/message_loop.cc
+++ b/base/message_loop/message_loop.cc
@@ -50,6 +50,7 @@
 // Logical events for Histogram profiling. Run with -message-loop-histogrammer
 // to get an accounting of messages and actions taken on each thread.
 const int kTaskRunEvent = 0x1;
+#if !defined(OS_NACL)
 const int kTimerEvent = 0x2;
 
 // Provide range of message IDs for use in histogramming and debug display.
@@ -83,6 +84,7 @@
 
   {-1, NULL}  // The list must be null terminated, per API to histogram.
 };
+#endif  // !defined(OS_NACL)
 
 bool enable_histogrammer_ = false;