Create variations param for RapporRollout to non-UMA users.

components/rappor/rappor_service.cc

Index: components/rappor/rappor_service.cc
diff --git a/components/rappor/rappor_service.cc b/components/rappor/rappor_service.cc
index 530909e35cfb20967c69d86aa9395206f3381a6b..c09e6edb102f498f0d8de03abf97466e80ad4c9b 100644
--- a/components/rappor/rappor_service.cc
+++ b/components/rappor/rappor_service.cc
@@ -35,6 +35,9 @@ const char kRapporRolloutFieldTrialName[] = "RapporRollout";
 // Constant for the finch parameter name for the server URL
 const char kRapporRolloutServerUrlParam[] = "ServerUrl";
 
+// Constant for the finch parameter name for the server URL
+const char kRapporRolloutRequireUmaParam[] = "RequireUma";
+
 // The rappor server's URL.
 const char kDefaultServerUrl[] = "https://clients4.google.com/rappor";
 
@@ -59,6 +62,19 @@ const RapporParameters kRapporParametersForType[NUM_RAPPOR_TYPES] = {
      rappor::PROBABILITY_25 /* Zero coin probability */},
 };
 
+bool IsRapporEnabled(const GURL& server_url, bool metrics_enabled) {

[Alexei Svitkine (slow), 2014/07/30 16:52:51]

Can this be part of GetServerUrl() given that already has a way to disable UMA
via returning an invalid URL?

Seems hard to follow if the logic is to split into different places.

[Steven Holte, 2014/08/05 03:09:36]

Done.

+  if (!server_url.is_valid()) {
+    DVLOG(1) << server_url.spec() << " is invalid.";
+    return false;
+  }
+  if (metrics_enabled) {

[Alexei Svitkine (slow), 2014/07/30 16:52:51]

Nit: No {}'s.

[Steven Holte, 2014/08/05 03:09:37]

Done.

+    return true;
+  }
+  return chrome_variations::GetVariationParamValue(

[Alexei Svitkine (slow), 2014/07/30 16:52:51]

Nit: Please rebase, this is now in namespace variations

[Steven Holte, 2014/08/05 03:09:37]

Done.

+      kRapporRolloutFieldTrialName,
+      kRapporRolloutRequireUmaParam) == "False";
+}
+
 }  // namespace
 
 RapporService::RapporService() : cohort_(-1) {}
@@ -68,11 +84,11 @@ RapporService::~RapporService() {
 }
 
 void RapporService::Start(PrefService* pref_service,
-                          net::URLRequestContextGetter* request_context) {
+                          net::URLRequestContextGetter* request_context,
+                          bool metrics_enabled) {
   const GURL server_url = GetServerUrl();
-  if (!server_url.is_valid()) {
-    DVLOG(1) << "RapporService not started: "
-             << server_url.spec() << " is invalid.";
+  if (!IsRapporEnabled(server_url, metrics_enabled)) {
+    DVLOG(1) << "RapporService not started.";
     return;
   }
   DVLOG(1) << "RapporService started. Reporting to " << server_url.spec();