Remove MetricsServiceObserver in favor of MetricsProvider.

The only user of this interface has been folded into
NetworkMetricsProvider.

BUG=409872

Review URL: https://codereview.chromium.org/532623003

Cr-Commit-Position: refs/heads/master@{#293149}

7 files changed, 5 insertions, 126 deletions

diff --git a/components/metrics.gypi b/components/metrics.gypi
index cf43cf7..25c17eb 100644
--- a/components/metrics.gypi
+++ b/components/metrics.gypi
@@ -43,8 +43,6 @@
         'metrics/metrics_service.cc',
         'metrics/metrics_service.h',
         'metrics/metrics_service_client.h',
-        'metrics/metrics_service_observer.cc',
-        'metrics/metrics_service_observer.h',
         'metrics/metrics_state_manager.cc',
         'metrics/metrics_state_manager.h',
         'metrics/metrics_switches.cc',
diff --git a/components/metrics/BUILD.gn b/components/metrics/BUILD.gn
index fa44a9b..cb25367 100644
--- a/components/metrics/BUILD.gn
+++ b/components/metrics/BUILD.gn
@@ -30,8 +30,6 @@ source_set("metrics") {
     "metrics_service.cc",
     "metrics_service.h",
     "metrics_service_client.h",
-    "metrics_service_observer.cc",
-    "metrics_service_observer.h",
     "metrics_state_manager.cc",
     "metrics_state_manager.h",
     "metrics_switches.cc",
diff --git a/components/metrics/metrics_service.cc b/components/metrics/metrics_service.cc
index fb800b6..daa7d5b 100644
--- a/components/metrics/metrics_service.cc
+++ b/components/metrics/metrics_service.cc
@@ -666,20 +666,8 @@ void MetricsService::GetUptimes(PrefService* pref,
   }
 }
 
-void MetricsService::AddObserver(MetricsServiceObserver* observer) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  observers_.AddObserver(observer);
-}
-
-void MetricsService::RemoveObserver(MetricsServiceObserver* observer) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  observers_.RemoveObserver(observer);
-}
-
 void MetricsService::NotifyOnDidCreateMetricsLog() {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  FOR_EACH_OBSERVER(
-      MetricsServiceObserver, observers_, OnDidCreateMetricsLog());
+  DCHECK(IsSingleThreaded());
   for (size_t i = 0; i < metrics_providers_.size(); ++i)
     metrics_providers_[i]->OnDidCreateMetricsLog();
 }
diff --git a/components/metrics/metrics_service.h b/components/metrics/metrics_service.h
index 3952fb3..4ed7ad1 100644
--- a/components/metrics/metrics_service.h
+++ b/components/metrics/metrics_service.h
@@ -21,14 +21,10 @@
 #include "base/metrics/histogram_flattener.h"
 #include "base/metrics/histogram_snapshot_manager.h"
 #include "base/metrics/user_metrics.h"
-#include "base/observer_list.h"
-#include "base/strings/string16.h"
-#include "base/threading/thread_checker.h"
 #include "base/time/time.h"
 #include "components/metrics/metrics_log.h"
 #include "components/metrics/metrics_log_manager.h"
 #include "components/metrics/metrics_provider.h"
-#include "components/metrics/metrics_service_observer.h"
 #include "components/variations/active_field_trials.h"
 
 class MetricsServiceAccessor;
@@ -283,9 +279,7 @@ class MetricsService : public base::HistogramFlattener {
   // Set up client ID, session ID, etc.
   void InitializeMetricsState();
 
-  // Registers/unregisters |observer| to receive MetricsLog notifications.
-  void AddObserver(MetricsServiceObserver* observer);
-  void RemoveObserver(MetricsServiceObserver* observer);
+  // Notifies providers when a new metrics log is created.
   void NotifyOnDidCreateMetricsLog();
 
   // Schedule the next save of LocalState information.  This is called
@@ -446,6 +440,9 @@ class MetricsService : public base::HistogramFlattener {
   // Stores the time of the last call to |GetUptimes()|.
   base::TimeTicks last_updated_time_;
 
+  // Field trial groups that map to Chrome configuration states.
+  SyntheticTrialGroups synthetic_trial_groups_;
+
   // Execution phase the browser is in.
   static ExecutionPhase execution_phase_;
 
@@ -453,18 +450,9 @@ class MetricsService : public base::HistogramFlattener {
   // exited-cleanly bit in the prefs.
   static ShutdownCleanliness clean_shutdown_status_;
 
-  // Field trial groups that map to Chrome configuration states.
-  SyntheticTrialGroups synthetic_trial_groups_;
-
-  ObserverList<MetricsServiceObserver> observers_;
-
-  // Confirms single-threaded access to |observers_| in debug builds.
-  base::ThreadChecker thread_checker_;
-
   friend class ::MetricsServiceAccessor;
 
   FRIEND_TEST_ALL_PREFIXES(MetricsServiceTest, IsPluginProcess);
-  FRIEND_TEST_ALL_PREFIXES(MetricsServiceTest, MetricsServiceObserver);
   FRIEND_TEST_ALL_PREFIXES(MetricsServiceTest,
                            PermutedEntropyCacheClearedWhenLowEntropyReset);
   FRIEND_TEST_ALL_PREFIXES(MetricsServiceTest, RegisterSyntheticTrial);
diff --git a/components/metrics/metrics_service_observer.cc b/components/metrics/metrics_service_observer.cc
deleted file mode 100644
index e7116f8..0000000
--- a/components/metrics/metrics_service_observer.cc
+++ /dev/null
@@ -1,15 +0,0 @@
-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "components/metrics/metrics_service_observer.h"
-
-namespace metrics {
-
-MetricsServiceObserver::MetricsServiceObserver() {
-}
-
-MetricsServiceObserver::~MetricsServiceObserver() {
-}
-
-}  // namespace metrics
diff --git a/components/metrics/metrics_service_observer.h b/components/metrics/metrics_service_observer.h
deleted file mode 100644
index a0efb84..0000000
--- a/components/metrics/metrics_service_observer.h
+++ /dev/null
@@ -1,29 +0,0 @@
-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef COMPONENTS_METRICS_METRICS_SERVICE_OBSERVER_H_
-#define COMPONENTS_METRICS_METRICS_SERVICE_OBSERVER_H_
-
-#include "base/macros.h"
-
-namespace metrics {
-
-// MetricsServiceObserver receives notifications from MetricsService.
-// An observer must be added, removed, and notified on the same thread.
-class MetricsServiceObserver {
- public:
-  // Called when a new MetricsLog is created.
-  virtual void OnDidCreateMetricsLog() = 0;
-
- protected:
-  MetricsServiceObserver();
-  virtual ~MetricsServiceObserver();
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(MetricsServiceObserver);
-};
-
-}  // namespace metrics
-
-#endif  // COMPONENTS_METRICS_METRICS_SERVICE_OBSERVER_H_
diff --git a/components/metrics/metrics_service_unittest.cc b/components/metrics/metrics_service_unittest.cc
index 2ee7e1d..e85f351 100644
--- a/components/metrics/metrics_service_unittest.cc
+++ b/components/metrics/metrics_service_unittest.cc
@@ -15,7 +15,6 @@
 #include "components/metrics/compression_utils.h"
 #include "components/metrics/metrics_log.h"
 #include "components/metrics/metrics_pref_names.h"
-#include "components/metrics/metrics_service_observer.h"
 #include "components/metrics/metrics_state_manager.h"
 #include "components/metrics/test_metrics_service_client.h"
 #include "components/variations/metrics_util.h"
@@ -130,22 +129,6 @@ class MetricsServiceTest : public testing::Test {
   DISALLOW_COPY_AND_ASSIGN(MetricsServiceTest);
 };
 
-class TestMetricsServiceObserver : public MetricsServiceObserver {
- public:
-  TestMetricsServiceObserver(): observed_(0) {}
-  virtual ~TestMetricsServiceObserver() {}
-
-  virtual void OnDidCreateMetricsLog() OVERRIDE {
-    ++observed_;
-  }
-  int observed() const { return observed_; }
-
- private:
-  int observed_;
-
-  DISALLOW_COPY_AND_ASSIGN(TestMetricsServiceObserver);
-};
-
 }  // namespace
 
 TEST_F(MetricsServiceTest, InitialStabilityLogAfterCleanShutDown) {
@@ -283,36 +266,4 @@ TEST_F(MetricsServiceTest, RegisterSyntheticTrial) {
   service.log_manager_.FinishCurrentLog();
 }
 
-TEST_F(MetricsServiceTest, MetricsServiceObserver) {
-  metrics::TestMetricsServiceClient client;
-  MetricsService service(GetMetricsStateManager(), &client, GetLocalState());
-  TestMetricsServiceObserver observer1;
-  TestMetricsServiceObserver observer2;
-
-  service.AddObserver(&observer1);
-  EXPECT_EQ(0, observer1.observed());
-  EXPECT_EQ(0, observer2.observed());
-
-  service.OpenNewLog();
-  EXPECT_EQ(1, observer1.observed());
-  EXPECT_EQ(0, observer2.observed());
-  service.log_manager_.FinishCurrentLog();
-
-  service.AddObserver(&observer2);
-
-  service.OpenNewLog();
-  EXPECT_EQ(2, observer1.observed());
-  EXPECT_EQ(1, observer2.observed());
-  service.log_manager_.FinishCurrentLog();
-
-  service.RemoveObserver(&observer1);
-
-  service.OpenNewLog();
-  EXPECT_EQ(2, observer1.observed());
-  EXPECT_EQ(2, observer2.observed());
-  service.log_manager_.FinishCurrentLog();
-
-  service.RemoveObserver(&observer2);
-}
-
 }  // namespace metrics