wm: Update namespace and header define guards.

src/platform/window_manager/metrics_reporter.cc

Index: src/platform/window_manager/metrics_reporter.cc
diff --git a/src/platform/window_manager/metrics_reporter.cc b/src/platform/window_manager/metrics_reporter.cc
index f5766a0003a043d029997e9cb0d4a679dfd8cfe8..aace150dadabb318be694a7a72a535730a6d4fe3 100644
--- a/src/platform/window_manager/metrics_reporter.cc
+++ b/src/platform/window_manager/metrics_reporter.cc
@@ -10,7 +10,7 @@
 #include "window_manager/system_metrics.pb.h"
 #include "window_manager/window.h"
 
-namespace chromeos {
+namespace window_manager {
 
 // This is the path to a file that's created by boot scripts, which contains
 // the boot time drawn from bootchart.
@@ -73,4 +73,4 @@ bool MetricsReporter::GatherBootTime(const std::string& filename,
   return true;
 }
 
-}  // namespace chromeos
+}  // namespace window_manager