bootstat: Remove custom uptime parser in favor of elapsedRealtime.

Refactored init/utils/boot_clock into base/chrono_utils.

Bug: 34352037
Test: none
Change-Id: Ied0c00867336b85922369d7ff37520e3d28fc61e
diff --git a/init/service.cpp b/init/service.cpp
index e186f27..cbdc4a8 100644
--- a/init/service.cpp
+++ b/init/service.cpp
@@ -32,6 +32,7 @@
 
 #include <selinux/selinux.h>
 
+#include <android-base/chrono_utils.h>
 #include <android-base/file.h>
 #include <android-base/parseint.h>
 #include <android-base/stringprintf.h>
@@ -47,6 +48,7 @@
 #include "property_service.h"
 #include "util.h"
 
+using android::base::boot_clock;
 using android::base::ParseInt;
 using android::base::StringPrintf;
 using android::base::WriteStringToFile;