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

chrome/browser/metrics/metrics_state_manager.h

Index: chrome/browser/metrics/metrics_state_manager.h
diff --git a/chrome/browser/metrics/metrics_state_manager.h b/chrome/browser/metrics/metrics_state_manager.h
index 5b2f954887a490623e14f957fc8a8577611e6390..bf8f1f4e6ba6ed7d6eef18ad59ee55bcd3504f06 100644
--- a/chrome/browser/metrics/metrics_state_manager.h
+++ b/chrome/browser/metrics/metrics_state_manager.h
@@ -8,6 +8,7 @@
 #include <string>
 
 #include "base/basictypes.h"
+#include "base/callback.h"
 #include "base/gtest_prod_util.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/metrics/field_trial.h"
@@ -27,8 +28,6 @@ class MetricsStateManager {
   virtual ~MetricsStateManager();
 
   // Returns true if the user opted in to sending metric reports.
-  // TODO(asvitkine): This function does not report the correct value on
-  // Android, see http://crbug.com/362192.
   bool IsMetricsReportingEnabled();
 
   // Returns the client ID for this client, or the empty string if the user is
@@ -55,7 +54,9 @@ class MetricsStateManager {
 
   // Creates the MetricsStateManager, enforcing that only a single instance
   // of the class exists at a time. Returns NULL if an instance exists already.
-  static scoped_ptr<MetricsStateManager> Create(PrefService* local_state);
+  static scoped_ptr<MetricsStateManager> Create(
+      PrefService* local_state,
+      const base::Callback<bool(void)>& is_reporting_enabled_callback);
 
   // Registers local state prefs used by this class.
   static void RegisterPrefs(PrefRegistrySimple* registry);
@@ -77,10 +78,13 @@ class MetricsStateManager {
     ENTROPY_SOURCE_HIGH,
   };
 
-  // Creates the MetricsStateManager with the given |local_state|. Clients
-  // should instead use Create(), which enforces a single instance of this class
-  // is alive at any given time.
-  explicit MetricsStateManager(PrefService* local_state);
+  // Creates the MetricsStateManager with the given |local_state|. Calls
+  // |is_reporting_enabled_callback| to query whether metrics reporting is
+  // enabled. Clients should instead use Create(), which enforces a single
+  // instance of this class is alive at any given time.
+  MetricsStateManager(
+      PrefService* local_state,
+      const base::Callback<bool(void)>& is_reporting_enabled_callback);
 
   // Returns the low entropy source for this client. This is a random value
   // that is non-identifying amongst browser clients. This method will
@@ -103,7 +107,9 @@ class MetricsStateManager {
   static bool instance_exists_;
 
   // Weak pointer to the local state prefs store.
-  PrefService* local_state_;
+  PrefService* const local_state_;

[Alexei Svitkine (slow), 2014/05/19 14:00:11]

Nit: I don't think this type of const for pointers is very commonly used. It
looks confusing to someone not used to seeing this syntax, so I'd rather not
have it. (Unless it is indeed more widely used in Chromium that I think it is.)

[Ilya Sherman, 2014/05/19 14:03:36]

Codesearch suggests it's used a lot.  I like const things, so keeping :)

+
+  const base::Callback<bool(void)> is_reporting_enabled_callback_;
 
   // The identifier that's sent to the server with the log reports.
   std::string client_id_;