[Metrics] Make MetricsStateManager take a callback param to check if UMA is enabled.

chrome/browser/metrics/metrics_state_manager_unittest.cc

Index: chrome/browser/metrics/metrics_state_manager_unittest.cc
diff --git a/chrome/browser/metrics/metrics_state_manager_unittest.cc b/chrome/browser/metrics/metrics_state_manager_unittest.cc
index 288d0872b88ed75cfc03d96a514620a1f5d22f1a..11b962241aa43b6eed6fcbe5cbe85582ccdc8007 100644
--- a/chrome/browser/metrics/metrics_state_manager_unittest.cc
+++ b/chrome/browser/metrics/metrics_state_manager_unittest.cc
@@ -7,6 +7,7 @@
 #include <ctype.h>
 #include <string>
 
+#include "base/bind.h"
 #include "base/command_line.h"
 #include "base/prefs/testing_pref_service.h"
 #include "chrome/common/chrome_switches.h"
@@ -19,18 +20,32 @@ namespace metrics {
 
 class MetricsStateManagerTest : public testing::Test {
  public:
-  MetricsStateManagerTest() {
+  MetricsStateManagerTest() : is_metrics_reporting_enabled_(false) {
     MetricsStateManager::RegisterPrefs(prefs_.registry());
   }
 
   scoped_ptr<MetricsStateManager> CreateStateManager() {
-    return MetricsStateManager::Create(&prefs_).Pass();
+    return MetricsStateManager::Create(
+        &prefs_,
+        base::Bind(&MetricsStateManagerTest::is_metrics_reporting_enabled,
+                   base::Unretained(this))).Pass();
+  }
+
+  // Sets metrics reporting as enabled for testing.
+  void EnableMetricsReporting() {
+    is_metrics_reporting_enabled_ = true;
   }
 
  protected:
   TestingPrefServiceSimple prefs_;
 
  private:
+  bool is_metrics_reporting_enabled() const {
+    return is_metrics_reporting_enabled_;
+  }
+
+  bool is_metrics_reporting_enabled_;
+
   DISALLOW_COPY_AND_ASSIGN(MetricsStateManagerTest);
 };
 
@@ -59,9 +74,7 @@ TEST_F(MetricsStateManagerTest, EntropySourceUsed_Low) {
 }
 
 TEST_F(MetricsStateManagerTest, EntropySourceUsed_High) {
-  CommandLine::ForCurrentProcess()->AppendSwitch(
-      switches::kEnableMetricsReportingForTesting);
-
+  EnableMetricsReporting();
   scoped_ptr<MetricsStateManager> state_manager(CreateStateManager());
   state_manager->CreateEntropyProvider();
   EXPECT_EQ(MetricsStateManager::ENTROPY_SOURCE_HIGH,