Implement UMA log throttling for cellular connections

components/metrics/metrics_service.h

Index: components/metrics/metrics_service.h
diff --git a/components/metrics/metrics_service.h b/components/metrics/metrics_service.h
index ce4102b8dfa36408fe037bd6772184d759a48a4e..72803adf186ada5fabef6278f22a2bb15eee9de8 100644
--- a/components/metrics/metrics_service.h
+++ b/components/metrics/metrics_service.h
@@ -27,6 +27,7 @@
 #include "base/time/time.h"
 #include "build/build_config.h"
 #include "components/metrics/clean_exit_beacon.h"
+#include "components/metrics/data_use_tracker.h"
 #include "components/metrics/metrics_log.h"
 #include "components/metrics/metrics_log_manager.h"
 #include "components/metrics/metrics_provider.h"
@@ -80,6 +81,12 @@ class MetricsService : public base::HistogramFlattener {
   MetricsService(MetricsStateManager* state_manager,
                  MetricsServiceClient* client,
                  PrefService* local_state);
+
+  // Creates the MetricsService as above with given |cellular_callback|
+  MetricsService(MetricsStateManager* state_manager,
+                 MetricsServiceClient* client,
+                 PrefService* local_state,
+                 base::Callback<void(bool*)> cellular_callback);
   ~MetricsService() override;
 
   // Initializes metrics recording state. Updates various bookkeeping values in
@@ -214,6 +221,8 @@ class MetricsService : public base::HistogramFlattener {
   // Pushes a log that has been generated by an external component.
   void PushExternalLog(const std::string& log);
 
+  base::WeakPtr<DataUseTracker> GetDataUseTracker();
+
  protected:
   // Exposed for testing.
   MetricsLogManager* log_manager() { return &log_manager_; }
@@ -468,7 +477,7 @@ class MetricsService : public base::HistogramFlattener {
   // Execution phase the browser is in.
   static ExecutionPhase execution_phase_;
 
-  // Reduntant marker to check that we completed our shutdown, and set the
+  // Redundant marker to check that we completed our shutdown, and set the
   // exited-cleanly bit in the prefs.
   static ShutdownCleanliness clean_shutdown_status_;
 
@@ -477,6 +486,13 @@ class MetricsService : public base::HistogramFlattener {
                            PermutedEntropyCacheClearedWhenLowEntropyReset);
   FRIEND_TEST_ALL_PREFIXES(MetricsServiceTest, RegisterSyntheticTrial);
 
+  // Assigns true to output param if current connection type is cellular and
+  // user is assigned to experimental group for enabled cellular uploads.
+  base::Callback<void(bool*)> cellular_callback_;
+
+  // Pointer used for obtaining data use pref updater callback on above layers.
+  scoped_ptr<DataUseTracker> data_use_tracker_;
+
   // Weak pointers factory used to post task on different threads. All weak
   // pointers managed by this factory have the same lifetime as MetricsService.
   base::WeakPtrFactory<MetricsService> self_ptr_factory_;