(Tiny) Make some execution_phase.cc includes windows only

components/metrics/execution_phase.cc

Index: components/metrics/execution_phase.cc
diff --git a/components/metrics/execution_phase.cc b/components/metrics/execution_phase.cc
index 98f9aee136e00cf13568de6bb70619ffae6bccb5..992ef820e77c945b17665f4390f49a1a6a924bfc 100644
--- a/components/metrics/execution_phase.cc
+++ b/components/metrics/execution_phase.cc
@@ -5,12 +5,15 @@
 #include "components/metrics/execution_phase.h"
 
 #include "build/build_config.h"
-#include "components/browser_watcher/stability_data_names.h"
-#include "components/browser_watcher/stability_debugging.h"
 #include "components/metrics/metrics_pref_names.h"
 #include "components/prefs/pref_registry_simple.h"
 #include "components/prefs/pref_service.h"
 
+#if defined(OS_WIN)
+#include "components/browser_watcher/stability_data_names.h"
+#include "components/browser_watcher/stability_debugging.h"
+#endif  // defined(OS_WIN)
+
 namespace metrics {
 
 ExecutionPhaseManager::ExecutionPhaseManager(PrefService* local_state)