Add experiment to exercise AffiliationService with dummy data, plus add related UMA histograms.

components/password_manager/core/browser/affiliation_utils.cc

Index: components/password_manager/core/browser/affiliation_utils.cc
diff --git a/components/password_manager/core/browser/affiliation_utils.cc b/components/password_manager/core/browser/affiliation_utils.cc
index 13c417aa4dd8704b9d2c318fb67e7f4dc74a8b84..fa911ffbd4ff2b0e8f40559988429dba883e836a 100644
--- a/components/password_manager/core/browser/affiliation_utils.cc
+++ b/components/password_manager/core/browser/affiliation_utils.cc
@@ -320,6 +320,17 @@ bool IsPropagatingPasswordChangesToWebCredentialsEnabled(
   return LowerCaseEqualsASCII(update_enabled, "enabled");
 }
 
+bool IsAffiliationRequestsForDummyFacetsEnabled(
+    const base::CommandLine& command_line) {
+  const std::string synthesizing_enabled = variations::GetVariationParamValue(
+      kFieldTrialName, "affiliation_requests_for_dummy_facets");

[Ilya Sherman, 2015/04/21 00:38:05]

Out of curiousity, what is the advantage of using a param over a direct field
trial to control a simple enabled/disabled state?

[engedy, 2015/04/21 18:29:07]

We will never get to initializing this sub-feature unless the main feature is
enabled. So if they are controlled by two separate field trials, then the
sub-feature is only enabled for the intersection of users. That seemed not so
nice in terms of easy of analyzing the results.

Also, it seemed clearer to just have one field trial, with multiple experiment
groups, with each one having some set of sub-features enabled. WDYT?

[Ilya Sherman, 2015/04/21 20:11:27]

Got it.  Yeah, that sounds reasonable.  Thanks for the explanation =)

+  if (command_line.HasSwitch(switches::kDisableAffiliationBasedMatching))
+    return false;
+  if (command_line.HasSwitch(switches::kEnableAffiliationBasedMatching))
+    return true;
+  return LowerCaseEqualsASCII(synthesizing_enabled, "enabled");
+}
+
 bool IsValidAndroidFacetURI(const std::string& url) {
   FacetURI facet = FacetURI::FromPotentiallyInvalidSpec(url);
   return facet.IsValidAndroidFacetURI();