Renaming and minor refactoring to make UMA default state functionality less error prone.

BUG=596185

TBR=sky, kmarshall

Review-Url: https://codereview.chromium.org/2055503002
Cr-Commit-Position: refs/heads/master@{#399920}
diff --git a/components/metrics/test_metrics_service_client.cc b/components/metrics/test_metrics_service_client.cc
index 438f2344..643880b 100644
--- a/components/metrics/test_metrics_service_client.cc
+++ b/components/metrics/test_metrics_service_client.cc
@@ -17,7 +17,7 @@
     : version_string_("5.0.322.0-64-devel"),
       product_(ChromeUserMetricsExtension::CHROME),
       reporting_is_managed_(false),
-      enable_default_(MetricsServiceClient::DEFAULT_UNKNOWN) {}
+      enable_default_(EnableMetricsDefault::DEFAULT_UNKNOWN) {}
 
 TestMetricsServiceClient::~TestMetricsServiceClient() {
 }
@@ -85,8 +85,8 @@
   return reporting_is_managed_;
 }
 
-MetricsServiceClient::EnableMetricsDefault
-TestMetricsServiceClient::GetDefaultOptIn() {
+EnableMetricsDefault
+TestMetricsServiceClient::GetMetricsReportingDefaultState() {
   return enable_default_;
 }