Add support for Blimp engine metrics reporting in development.

components/metrics/metrics_log.cc

Index: components/metrics/metrics_log.cc
diff --git a/components/metrics/metrics_log.cc b/components/metrics/metrics_log.cc
index 97774127d81a4ef3f44d2eb22f2d372f85a11e2e..f0bf415b38d12f5f23ae34c0e01b3b79dea83ed5 100644
--- a/components/metrics/metrics_log.cc
+++ b/components/metrics/metrics_log.cc
@@ -325,9 +325,14 @@ void MetricsLog::RecordEnvironment(
   hardware->set_dll_base(reinterpret_cast<uint64_t>(&__ImageBase));
 #endif
 
+#if defined(OVERRIDE_OS_NAME_TO_BLIMP)
+  os->set_name("Blimp");

[Alexei Svitkine (slow), 2016/03/07 21:17:44]

Note: That this will require server-side changes to support it. Happy to assist
you in making those changes (I think I pointed at the relevant code snippet we
have on the doc where we discussed it - so feel free to change that and send me
the CL.)

[Jess, 2016/03/07 22:28:08]

Acknowledged.

+#else
   SystemProfileProto::OS* os = system_profile->mutable_os();
   std::string os_name = base::SysInfo::OperatingSystemName();
   os->set_name(os_name);
+#endif
+
   os->set_version(base::SysInfo::OperatingSystemVersion());
 #if defined(OS_ANDROID)
   os->set_fingerprint(