Enable system trace clock use on chrome os.

Enable CLOCK_SYSTEM_TRACE use when built with chromeos=1.  Handle the
case of building for chrome os but running on a non-chromeos platform
by handling clock_gettime failure and falling back to HighResNow.

BUG=chromium-os:30502
TEST=base_unittests + verify chrome:tracing works w/ a chromeos=1 build on linux and on cros (using the correct clock in each case)

Change-Id: I1627e414524c04db27ddf2a62798a802ea440919


Review URL: https://chromiumcodereview.appspot.com/10384154

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@137300 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 8 insertions, 4 deletions

diff --git a/base/time_posix.cc b/base/time_posix.cc
index b8f1385..18203cf 100644
--- a/base/time_posix.cc
+++ b/base/time_posix.cc
@@ -228,7 +228,11 @@ TimeTicks TimeTicks::HighResNow() {
   return Now();
 }
 
-#if defined(OS_POSIX) && defined(CLOCK_SYSTEM_TRACE)
+#if defined(OS_CHROMEOS)
+// Force definition of the system trace clock; it is a chromeos-only api
+// at the moment and surfacing it in the right place requires mucking
+// with glibc et al.
+#define CLOCK_SYSTEM_TRACE 11
 
 // static
 TimeTicks TimeTicks::NowFromSystemTraceTime() {
@@ -236,7 +240,7 @@ TimeTicks TimeTicks::NowFromSystemTraceTime() {
 
   struct timespec ts;
   if (clock_gettime(CLOCK_SYSTEM_TRACE, &ts) != 0) {
-    NOTREACHED() << "clock_gettime(CLOCK_SYSTEM_TRACE) failed.";
+    // NB: fall-back for a chrome os build running on linux
     return HighResNow();
   }
 
@@ -247,14 +251,14 @@ TimeTicks TimeTicks::NowFromSystemTraceTime() {
   return TimeTicks(absolute_micro);
 }
 
-#else // !(defined(OS_POSIX) && defined(CLOCK_SYSTEM_TRACE))
+#else // !defined(OS_CHROMEOS)
 
 // static
 TimeTicks TimeTicks::NowFromSystemTraceTime() {
   return HighResNow();
 }
 
-#endif // defined(OS_POSIX) && defined(CLOCK_SYSTEM_TRACE)
+#endif // defined(OS_CHROMEOS)
 
 #endif  // !OS_MACOSX