diff --git a/policy_manager/fake_device_policy_provider.h b/policy_manager/fake_device_policy_provider.h
index 4863ae5..252a5e5 100644
--- a/policy_manager/fake_device_policy_provider.h
+++ b/policy_manager/fake_device_policy_provider.h
@@ -60,9 +60,7 @@
   }
 
  private:
-  virtual bool DoInit() override {
-    return true;
-  }
+  virtual bool DoInit() override { return true; }
 
   FakeVariable<bool> var_device_policy_is_loaded_{
       "policy_is_loaded", kVariableModePoll};
diff --git a/policy_manager/fake_random_provider.h b/policy_manager/fake_random_provider.h
index 8d98689..64f08a4 100644
--- a/policy_manager/fake_random_provider.h
+++ b/policy_manager/fake_random_provider.h
@@ -15,13 +15,13 @@
  public:
   FakeRandomProvider() {}
 
- protected:
-  virtual bool DoInit() {
-    set_var_seed(new FakeVariable<uint64_t>("seed", kVariableModeConst));
-    return true;
-  }
+  virtual FakeVariable<uint64_t>* var_seed() override { return &var_seed_; }
 
  private:
+  virtual bool DoInit() override { return true; }
+
+  FakeVariable<uint64_t> var_seed_{"seed", kVariableModePoll};
+
   DISALLOW_COPY_AND_ASSIGN(FakeRandomProvider);
 };
 
diff --git a/policy_manager/fake_shill_provider.h b/policy_manager/fake_shill_provider.h
index d15668d..c18b0d2 100644
--- a/policy_manager/fake_shill_provider.h
+++ b/policy_manager/fake_shill_provider.h
@@ -15,27 +15,26 @@
  public:
   FakeShillProvider() {}
 
-  virtual inline FakeVariable<bool>* var_is_connected() override {
+  virtual FakeVariable<bool>* var_is_connected() override {
     return &var_is_connected_;
   }
 
-  virtual inline FakeVariable<ConnectionType>* var_conn_type() override {
+  virtual FakeVariable<ConnectionType>* var_conn_type() override {
     return &var_conn_type_;
   }
 
-  virtual inline FakeVariable<ConnectionTethering>*
+  virtual FakeVariable<ConnectionTethering>*
       var_conn_tethering() override {
     return &var_conn_tethering_;
   }
 
-  virtual inline FakeVariable<base::Time>* var_conn_last_changed() override {
+  virtual FakeVariable<base::Time>* var_conn_last_changed() override {
     return &var_conn_last_changed_;
   }
 
- protected:
-  virtual bool DoInit() { return true; }
-
  private:
+  virtual bool DoInit() override { return true; }
+
   FakeVariable<bool> var_is_connected_{"is_connected", kVariableModePoll};
   FakeVariable<ConnectionType> var_conn_type_{"conn_type", kVariableModePoll};
   FakeVariable<ConnectionTethering> var_conn_tethering_{
diff --git a/policy_manager/fake_system_provider.h b/policy_manager/fake_system_provider.h
index 8e6b92a..fbdff49 100644
--- a/policy_manager/fake_system_provider.h
+++ b/policy_manager/fake_system_provider.h
@@ -15,16 +15,22 @@
  public:
   FakeSystemProvider() {}
 
- protected:
-  virtual bool DoInit() {
-    set_var_is_normal_boot_mode(
-        new FakeVariable<bool>("is_normal_boot_mode", kVariableModeConst));
-    set_var_is_official_build(
-        new FakeVariable<bool>("is_official_build", kVariableModeConst));
-    return true;
+  virtual FakeVariable<bool>* var_is_normal_boot_mode() override {
+    return &var_is_normal_boot_mode_;
+  }
+
+  virtual FakeVariable<bool>* var_is_official_build() override {
+    return &var_is_official_build_;
   }
 
  private:
+  virtual bool DoInit() override { return true; }
+
+  FakeVariable<bool> var_is_normal_boot_mode_{
+      "is_normal_boot_mode", kVariableModeConst};
+  FakeVariable<bool> var_is_official_build_{
+      "is_official_build", kVariableModeConst};
+
   DISALLOW_COPY_AND_ASSIGN(FakeSystemProvider);
 };
 
diff --git a/policy_manager/fake_time_provider.h b/policy_manager/fake_time_provider.h
index 6797f5c..a73346a 100644
--- a/policy_manager/fake_time_provider.h
+++ b/policy_manager/fake_time_provider.h
@@ -15,16 +15,20 @@
  public:
   FakeTimeProvider() {}
 
- protected:
-  virtual bool DoInit() {
-    set_var_curr_date(
-        new FakeVariable<base::Time>("curr_date", kVariableModePoll));
-    set_var_curr_hour(
-        new FakeVariable<int>("curr_hour", kVariableModePoll));
-    return true;
+  virtual FakeVariable<base::Time>* var_curr_date() override {
+    return &var_curr_date_;
+  }
+
+  virtual FakeVariable<int>* var_curr_hour() override {
+    return &var_curr_hour_;
   }
 
  private:
+  virtual bool DoInit() override { return true; }
+
+  FakeVariable<base::Time> var_curr_date_{"curr_date", kVariableModePoll};
+  FakeVariable<int> var_curr_hour_{"curr_hour", kVariableModePoll};
+
   DISALLOW_COPY_AND_ASSIGN(FakeTimeProvider);
 };
 
diff --git a/policy_manager/fake_updater_provider.h b/policy_manager/fake_updater_provider.h
index d208574..aa12ce7 100644
--- a/policy_manager/fake_updater_provider.h
+++ b/policy_manager/fake_updater_provider.h
@@ -55,10 +55,9 @@
     return &var_cellular_enabled_;
   }
 
- protected:
+ private:
   virtual bool DoInit() { return true; }
 
- private:
   FakeVariable<base::Time> var_last_checked_time_{
     "last_checked_time", kVariableModePoll};
   FakeVariable<base::Time> var_update_completed_time_{
diff --git a/policy_manager/random_provider.h b/policy_manager/random_provider.h
index b184cf5..a5d76f1 100644
--- a/policy_manager/random_provider.h
+++ b/policy_manager/random_provider.h
@@ -15,23 +15,18 @@
 // Provider of random values.
 class RandomProvider : public Provider {
  public:
+  virtual ~RandomProvider() {}
+
   // Return a random number every time it is requested. Note that values
   // returned by the variables are cached by the EvaluationContext, so the
   // returned value will be the same during the same policy request. If more
   // random values are needed use a PRNG seeded with this value.
-  Variable<uint64_t>* var_seed() const { return var_seed_.get(); }
+  virtual Variable<uint64_t>* var_seed() = 0;
 
  protected:
   RandomProvider() {}
 
-  void set_var_seed(Variable<uint64_t>* var_seed) {
-    var_seed_.reset(var_seed);
-  }
-
  private:
-  // The seed() scoped variable.
-  scoped_ptr<Variable<uint64_t>> var_seed_;
-
   DISALLOW_COPY_AND_ASSIGN(RandomProvider);
 };
 
diff --git a/policy_manager/real_random_provider.cc b/policy_manager/real_random_provider.cc
index 4c8ae85..3ab4ff4 100644
--- a/policy_manager/real_random_provider.cc
+++ b/policy_manager/real_random_provider.cc
@@ -67,7 +67,7 @@
   FILE* fp = fopen(kRandomDevice, "r");
   if (!fp)
     return false;
-  set_var_seed(new RandomSeedVariable("seed", fp));
+  var_seed_.reset(new RandomSeedVariable("seed", fp));
   return true;
 }
 
diff --git a/policy_manager/real_random_provider.h b/policy_manager/real_random_provider.h
index 75c8f6e..7dd8fab 100644
--- a/policy_manager/real_random_provider.h
+++ b/policy_manager/real_random_provider.h
@@ -14,11 +14,14 @@
  public:
   RealRandomProvider() {}
 
- protected:
-  // Initializes all the variables.
-  virtual bool DoInit(void);
+  virtual Variable<uint64_t>* var_seed() override { return var_seed_.get(); }
 
  private:
+  virtual bool DoInit(void) override;
+
+  // The seed() scoped variable.
+  scoped_ptr<Variable<uint64_t>> var_seed_;
+
   DISALLOW_COPY_AND_ASSIGN(RealRandomProvider);
 };
 
diff --git a/policy_manager/real_shill_provider.h b/policy_manager/real_shill_provider.h
index cd5ee06..9c15700 100644
--- a/policy_manager/real_shill_provider.h
+++ b/policy_manager/real_shill_provider.h
@@ -31,19 +31,19 @@
 
   virtual ~RealShillProvider();
 
-  virtual inline Variable<bool>* var_is_connected() override {
+  virtual Variable<bool>* var_is_connected() override {
     return &var_is_connected_;
   }
 
-  virtual inline Variable<ConnectionType>* var_conn_type() override {
+  virtual Variable<ConnectionType>* var_conn_type() override {
     return &var_conn_type_;
   }
 
-  virtual inline Variable<ConnectionTethering>* var_conn_tethering() override {
+  virtual Variable<ConnectionTethering>* var_conn_tethering() override {
     return &var_conn_tethering_;
   }
 
-  virtual inline Variable<base::Time>* var_conn_last_changed() override {
+  virtual Variable<base::Time>* var_conn_last_changed() override {
     return &var_conn_last_changed_;
   }
 
@@ -52,10 +52,9 @@
   static ConnectionTethering ParseConnectionTethering(
       const char* tethering_str);
 
- protected:
+ private:
   virtual bool DoInit() override;
 
- private:
   // Return a DBus proxy for a given |path| and |interface| within shill.
   DBusGProxy* GetProxy(const char* path, const char* interface);
 
diff --git a/policy_manager/real_system_provider.cc b/policy_manager/real_system_provider.cc
index 72669ff..ade9b6b 100644
--- a/policy_manager/real_system_provider.cc
+++ b/policy_manager/real_system_provider.cc
@@ -19,11 +19,11 @@
 namespace chromeos_policy_manager {
 
 bool RealSystemProvider::DoInit() {
-  set_var_is_normal_boot_mode(
+  var_is_normal_boot_mode_.reset(
       new ConstCopyVariable<bool>("is_normal_boot_mode",
                                   VbGetSystemPropertyInt("devsw_boot") != 0));
 
-  set_var_is_official_build(
+  var_is_official_build_.reset(
       new ConstCopyVariable<bool>("var_is_official_build",
                                   VbGetSystemPropertyInt("debug_build") == 0));
 
diff --git a/policy_manager/real_system_provider.h b/policy_manager/real_system_provider.h
index d5534cb..2de07a1 100644
--- a/policy_manager/real_system_provider.h
+++ b/policy_manager/real_system_provider.h
@@ -16,9 +16,20 @@
  public:
   RealSystemProvider() {}
 
+  virtual Variable<bool>* var_is_normal_boot_mode() override {
+    return var_is_normal_boot_mode_.get();
+  }
+
+  virtual Variable<bool>* var_is_official_build() override {
+    return var_is_official_build_.get();
+  }
+
  private:
   virtual bool DoInit() override;
 
+  scoped_ptr<Variable<bool>> var_is_normal_boot_mode_;
+  scoped_ptr<Variable<bool>> var_is_official_build_;
+
   DISALLOW_COPY_AND_ASSIGN(RealSystemProvider);
 };
 
diff --git a/policy_manager/real_time_provider.cc b/policy_manager/real_time_provider.cc
index d66dd6f..b2ddd2f 100644
--- a/policy_manager/real_time_provider.cc
+++ b/policy_manager/real_time_provider.cc
@@ -61,8 +61,8 @@
 };
 
 bool RealTimeProvider::DoInit() {
-  set_var_curr_date(new CurrDateVariable("curr_date", clock_));
-  set_var_curr_hour(new CurrHourVariable("curr_hour", clock_));
+  var_curr_date_.reset(new CurrDateVariable("curr_date", clock_));
+  var_curr_hour_.reset(new CurrHourVariable("curr_hour", clock_));
   return true;
 }
 
diff --git a/policy_manager/real_time_provider.h b/policy_manager/real_time_provider.h
index 49d8896..69b0fe9 100644
--- a/policy_manager/real_time_provider.h
+++ b/policy_manager/real_time_provider.h
@@ -18,13 +18,23 @@
   RealTimeProvider(chromeos_update_engine::ClockInterface* clock)
       : clock_(clock) {}
 
- protected:
-  virtual bool DoInit();
+  virtual Variable<base::Time>* var_curr_date() override {
+    return var_curr_date_.get();
+  }
+
+  virtual Variable<int>* var_curr_hour() override {
+    return var_curr_hour_.get();
+  }
 
  private:
-  // A clock abstraction (mockable).
+  virtual bool DoInit() override;
+
+  // A clock abstraction (fakeable).
   chromeos_update_engine::ClockInterface* const clock_;
 
+  scoped_ptr<Variable<base::Time>> var_curr_date_;
+  scoped_ptr<Variable<int>> var_curr_hour_;
+
   DISALLOW_COPY_AND_ASSIGN(RealTimeProvider);
 };
 
diff --git a/policy_manager/real_updater_provider.h b/policy_manager/real_updater_provider.h
index 1b24e16..7ff8e69 100644
--- a/policy_manager/real_updater_provider.h
+++ b/policy_manager/real_updater_provider.h
@@ -62,10 +62,9 @@
     return var_cellular_enabled_.get();
   }
 
- protected:
+ private:
   virtual bool DoInit() { return true; }
 
- private:
   // A pointer to the update engine's system state aggregator.
   chromeos_update_engine::SystemState* system_state_;
 
diff --git a/policy_manager/shill_provider.h b/policy_manager/shill_provider.h
index b53266f..967faae 100644
--- a/policy_manager/shill_provider.h
+++ b/policy_manager/shill_provider.h
@@ -32,6 +32,8 @@
 // Provider for networking related information.
 class ShillProvider : public Provider {
  public:
+  virtual ~ShillProvider() {}
+
   // A variable returning whether we currently have network connectivity.
   virtual Variable<bool>* var_is_connected() = 0;
 
@@ -49,6 +51,9 @@
 
  protected:
   ShillProvider() {}
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ShillProvider);
 };
 
 }  // namespace chromeos_policy_manager
diff --git a/policy_manager/system_provider.h b/policy_manager/system_provider.h
index b7f93c0..d319b8c 100644
--- a/policy_manager/system_provider.h
+++ b/policy_manager/system_provider.h
@@ -16,33 +16,20 @@
 // reported by crossystem, the kernel boot command line and the partition table.
 class SystemProvider : public Provider {
  public:
+  virtual ~SystemProvider() {}
+
   // Returns true if the boot mode is normal or if it's unable to
   // determine the boot mode. Returns false if the boot mode is
   // developer.
-  Variable<bool>* var_is_normal_boot_mode() const {
-    return var_is_normal_boot_mode_.get();
-  }
+  virtual Variable<bool>* var_is_normal_boot_mode() = 0;
 
   // Returns whether this is an official Chrome OS build.
-  Variable<bool>* var_is_official_build() const {
-    return var_is_official_build_.get();
-  }
+  virtual Variable<bool>* var_is_official_build() = 0;
 
  protected:
   SystemProvider() {}
 
-  void set_var_is_normal_boot_mode(Variable<bool>* var_is_normal_boot_mode) {
-    var_is_normal_boot_mode_.reset(var_is_normal_boot_mode);
-  }
-
-  void set_var_is_official_build(Variable<bool>* var_is_official_build) {
-    var_is_official_build_.reset(var_is_official_build);
-  }
-
  private:
-  scoped_ptr<Variable<bool>> var_is_normal_boot_mode_;
-  scoped_ptr<Variable<bool>> var_is_official_build_;
-
   DISALLOW_COPY_AND_ASSIGN(SystemProvider);
 };
 
diff --git a/policy_manager/time_provider.h b/policy_manager/time_provider.h
index 7b8bbd9..8349c01 100644
--- a/policy_manager/time_provider.h
+++ b/policy_manager/time_provider.h
@@ -16,16 +16,14 @@
 // Provider for time related information.
 class TimeProvider : public Provider {
  public:
+  virtual ~TimeProvider() {}
+
   // Returns the current date. The time of day component will be zero.
-  Variable<base::Time>* var_curr_date() const {
-    return var_curr_date_.get();
-  }
+  virtual Variable<base::Time>* var_curr_date() = 0;
 
   // Returns the current hour (0 to 23) in local time. The type is int to keep
   // consistent with base::Time.
-  Variable<int>* var_curr_hour() const {
-    return var_curr_hour_.get();
-  }
+  virtual Variable<int>* var_curr_hour() = 0;
 
   // TODO(garnold) Implement a method/variable for querying whether a given
   // point in time was reached.
@@ -33,18 +31,7 @@
  protected:
   TimeProvider() {}
 
-  void set_var_curr_date(Variable<base::Time>* var_curr_date) {
-    var_curr_date_.reset(var_curr_date);
-  }
-
-  void set_var_curr_hour(Variable<int>* var_curr_hour) {
-    var_curr_hour_.reset(var_curr_hour);
-  }
-
  private:
-  scoped_ptr<Variable<base::Time>> var_curr_date_;
-  scoped_ptr<Variable<int>> var_curr_hour_;
-
   DISALLOW_COPY_AND_ASSIGN(TimeProvider);
 };
 
diff --git a/policy_manager/updater_provider.h b/policy_manager/updater_provider.h
index fa2382f..75f1fb8 100644
--- a/policy_manager/updater_provider.h
+++ b/policy_manager/updater_provider.h
@@ -30,6 +30,8 @@
 // Provider for Chrome OS update related information.
 class UpdaterProvider : public Provider {
  public:
+  virtual ~UpdaterProvider() {}
+
   // A variable returning the last update check time.
   virtual Variable<base::Time>* var_last_checked_time() = 0;
 
@@ -68,6 +70,12 @@
 
   // A variable indicating whether updates are allowed over a cellular network.
   virtual Variable<bool>* var_cellular_enabled() = 0;
+
+ protected:
+  UpdaterProvider() {}
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(UpdaterProvider);
 };
 
 }  // namespace chromeos_policy_manager