Retrieve client_id from GoogleUpdateSettings when its missing from Local State.

chrome/browser/metrics/metrics_services_manager.cc

Index: chrome/browser/metrics/metrics_services_manager.cc
diff --git a/chrome/browser/metrics/metrics_services_manager.cc b/chrome/browser/metrics/metrics_services_manager.cc
index 8278913da7da438199e2c1b3f363649bc54148d3..74d37107e154e3edde01268538c08bbb0d8fffde 100644
--- a/chrome/browser/metrics/metrics_services_manager.cc
+++ b/chrome/browser/metrics/metrics_services_manager.cc
@@ -4,12 +4,16 @@
 
 #include "chrome/browser/metrics/metrics_services_manager.h"
 
+#include <string>
+
 #include "base/command_line.h"
+#include "base/logging.h"
 #include "base/prefs/pref_service.h"
 #include "chrome/browser/metrics/chrome_metrics_service_client.h"
 #include "chrome/browser/metrics/variations/variations_service.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/pref_names.h"
+#include "chrome/installer/util/google_update_settings.h"
 #include "components/metrics/metrics_service.h"
 #include "components/metrics/metrics_state_manager.h"
 #include "components/rappor/rappor_service.h"
@@ -70,7 +74,9 @@ metrics::MetricsStateManager* MetricsServicesManager::GetMetricsStateManager() {
     metrics_state_manager_ = metrics::MetricsStateManager::Create(
         local_state_,
         base::Bind(&MetricsServicesManager::IsMetricsReportingEnabled,
-                   base::Unretained(this)));
+                   base::Unretained(this)),
+        base::Bind(&GoogleUpdateSettings::StoreMetricsClientInfo),
+        base::Bind(&GoogleUpdateSettings::LoadMetricsClientInfo));

[Alexei Svitkine (slow), 2014/07/15 12:53:25]

Just to confirm, are these two OK to run on UI thread?

[gab, 2014/07/15 20:50:05]

On Windows yes (registry access is not considered IO).

On Posix (google_update_settings_posix.cc), a file is used, but this was already
the case before this CL and it uses base::WriteFile which has ThreadRestrictions
checks (so I've been guessing it was okay...).

[Alexei Svitkine (slow), 2014/07/16 14:43:58]

Hmm, I think the POSIX code is problematic. I'm sure it will result in
AssertIOAllowed() triggering in a debug build. But it looks like only
StoreMetricsClientInfo() does IO, but LoadMetricsClientInfo doesn't.

In which case, I think we can fix this by making the POSIX impl of
StoreMetricsClientInfo() post a task to the blocking pool where IO is allowed.

[gab, 2014/07/16 15:51:43]

Right, but GoogleUpdateSettings::StoreMetricsClientInfo() was already called
from ChromeMetricsServiceClient::SetMetricsClientId() before this CL.

I'm happy to fix this in my follow-up for POSIX (see this CL's description), but
for now I don't think this CL makes this worse on POSIX and I'd rather avoid
touching the POSIX impl in this CL.

[Alexei Svitkine (slow), 2014/07/16 19:18:22]

SGTM, but please fix in a follow-up CL.

   }
   return metrics_state_manager_.get();
 }