diff --git a/connection_manager.cc b/connection_manager.cc
index 62bb11e..45b6467 100644
--- a/connection_manager.cc
+++ b/connection_manager.cc
@@ -253,8 +253,9 @@
   }
 }
 
+// static
 const char* ConnectionManager::StringForConnectionType(
-    NetworkConnectionType type) const {
+    NetworkConnectionType type) {
   switch (type) {
     case NetworkConnectionType::kEthernet:
       return shill::kTypeEthernet;
@@ -272,8 +273,8 @@
   return "Unknown";
 }
 
-const char* ConnectionManager::StringForTethering(
-    NetworkTethering tethering) const {
+// static
+const char* ConnectionManager::StringForTethering(NetworkTethering tethering) {
   switch (tethering) {
     case NetworkTethering::kNotDetected:
       return shill::kTetheringNotDetectedState;
diff --git a/connection_manager.h b/connection_manager.h
index 687759e..551c4f3 100644
--- a/connection_manager.h
+++ b/connection_manager.h
@@ -7,59 +7,36 @@
 
 #include <base/macros.h>
 
+#include "update_engine/connection_manager_interface.h"
 #include "update_engine/dbus_wrapper_interface.h"
 
 namespace chromeos_update_engine {
 
-enum class NetworkConnectionType {
-  kEthernet = 0,
-  kWifi,
-  kWimax,
-  kBluetooth,
-  kCellular,
-  kUnknown
-};
-
-enum class NetworkTethering {
-  kNotDetected = 0,
-  kSuspected,
-  kConfirmed,
-  kUnknown
-};
-
 class SystemState;
 
-// This class exposes a generic interface to the connection manager
-// (e.g FlimFlam, Shill, etc.) to consolidate all connection-related
-// logic in update_engine.
-class ConnectionManager {
+// This class implements the concrete class that talks with the connection
+// manager (shill) over DBus.
+class ConnectionManager : public ConnectionManagerInterface {
  public:
-  // Constructs a new ConnectionManager object initialized with the
-  // given system state.
-  explicit ConnectionManager(SystemState* system_state);
-  virtual ~ConnectionManager() = default;
-
-  // Populates |out_type| with the type of the network connection
-  // that we are currently connected and |out_tethering| with the estimate of
-  // whether that network is being tethered. The dbus_iface is used to query
-  // the real connection manager (e.g shill).
-  virtual bool GetConnectionProperties(DBusWrapperInterface* dbus_iface,
-                                       NetworkConnectionType* out_type,
-                                       NetworkTethering* out_tethering) const;
-
-  // Returns true if we're allowed to update the system when we're
-  // connected to the internet through the given network connection type and the
-  // given tethering state.
-  virtual bool IsUpdateAllowedOver(NetworkConnectionType type,
-                                   NetworkTethering tethering) const;
-
   // Returns the string representation corresponding to the given
   // connection type.
-  virtual const char* StringForConnectionType(NetworkConnectionType type) const;
+  static const char* StringForConnectionType(NetworkConnectionType type);
 
   // Returns the string representation corresponding to the given tethering
   // state.
-  virtual const char* StringForTethering(NetworkTethering tethering) const;
+  static const char* StringForTethering(NetworkTethering tethering);
+
+  // Constructs a new ConnectionManager object initialized with the
+  // given system state.
+  explicit ConnectionManager(SystemState* system_state);
+  ~ConnectionManager() override = default;
+
+  // ConnectionManagerInterface overrides
+  bool GetConnectionProperties(DBusWrapperInterface* dbus_iface,
+                               NetworkConnectionType* out_type,
+                               NetworkTethering* out_tethering) const override;
+  bool IsUpdateAllowedOver(NetworkConnectionType type,
+                           NetworkTethering tethering) const override;
 
  private:
   // The global context for update_engine
diff --git a/connection_manager_interface.h b/connection_manager_interface.h
new file mode 100644
index 0000000..aa04946
--- /dev/null
+++ b/connection_manager_interface.h
@@ -0,0 +1,60 @@
+// Copyright 2015 The Chromium OS 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 UPDATE_ENGINE_CONNECTION_MANAGER_INTERFACE_H_
+#define UPDATE_ENGINE_CONNECTION_MANAGER_INTERFACE_H_
+
+#include <base/macros.h>
+
+#include "update_engine/dbus_wrapper_interface.h"
+
+namespace chromeos_update_engine {
+
+enum class NetworkConnectionType {
+  kEthernet,
+  kWifi,
+  kWimax,
+  kBluetooth,
+  kCellular,
+  kUnknown
+};
+
+enum class NetworkTethering {
+  kNotDetected,
+  kSuspected,
+  kConfirmed,
+  kUnknown
+};
+
+// This class exposes a generic interface to the connection manager
+// (e.g FlimFlam, Shill, etc.) to consolidate all connection-related
+// logic in update_engine.
+class ConnectionManagerInterface {
+ public:
+  virtual ~ConnectionManagerInterface() = default;
+
+  // Populates |out_type| with the type of the network connection
+  // that we are currently connected and |out_tethering| with the estimate of
+  // whether that network is being tethered.
+  virtual bool GetConnectionProperties(
+      DBusWrapperInterface* dbus_iface,
+      NetworkConnectionType* out_type,
+      NetworkTethering* out_tethering) const = 0;
+
+  // Returns true if we're allowed to update the system when we're
+  // connected to the internet through the given network connection type and the
+  // given tethering state.
+  virtual bool IsUpdateAllowedOver(NetworkConnectionType type,
+                                   NetworkTethering tethering) const = 0;
+
+ protected:
+  ConnectionManagerInterface() = default;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ConnectionManagerInterface);
+};
+
+}  // namespace chromeos_update_engine
+
+#endif  // UPDATE_ENGINE_CONNECTION_MANAGER_INTERFACE_H_
diff --git a/dbus_service.cc b/dbus_service.cc
index 0dbff6b..d77ea31 100644
--- a/dbus_service.cc
+++ b/dbus_service.cc
@@ -13,7 +13,7 @@
 #include <policy/device_policy.h>
 
 #include "update_engine/clock_interface.h"
-#include "update_engine/connection_manager.h"
+#include "update_engine/connection_manager_interface.h"
 #include "update_engine/dbus_constants.h"
 #include "update_engine/hardware_interface.h"
 #include "update_engine/omaha_request_params.h"
@@ -408,7 +408,7 @@
     UpdateEngineService* self,
     gboolean* allowed,
     GError **error) {
-  chromeos_update_engine::ConnectionManager* cm =
+  chromeos_update_engine::ConnectionManagerInterface* cm =
       self->system_state_->connection_manager();
 
   // The device_policy is loaded in a lazy way before an update check and is
diff --git a/fake_system_state.cc b/fake_system_state.cc
index 8747a59..c10dca1 100644
--- a/fake_system_state.cc
+++ b/fake_system_state.cc
@@ -9,8 +9,7 @@
 // Mock the SystemStateInterface so that we could lie that
 // OOBE is completed even when there's no such marker file, etc.
 FakeSystemState::FakeSystemState()
-  : mock_connection_manager_(this),
-    mock_update_attempter_(this, &dbus_),
+  : mock_update_attempter_(this, &dbus_),
     mock_request_params_(this),
     fake_update_manager_(&fake_clock_),
     clock_(&fake_clock_),
diff --git a/fake_system_state.h b/fake_system_state.h
index 84c37fc..1f3f58f 100644
--- a/fake_system_state.h
+++ b/fake_system_state.h
@@ -45,7 +45,7 @@
     return device_policy_;
   }
 
-  inline ConnectionManager* connection_manager() override {
+  inline ConnectionManagerInterface* connection_manager() override {
     return connection_manager_;
   }
 
@@ -89,7 +89,8 @@
     clock_ = clock ? clock : &fake_clock_;
   }
 
-  inline void set_connection_manager(ConnectionManager* connection_manager) {
+  inline void set_connection_manager(
+      ConnectionManagerInterface* connection_manager) {
     connection_manager_ = (connection_manager ? connection_manager :
                            &mock_connection_manager_);
   }
@@ -215,7 +216,7 @@
   // Pointers to objects that client code can override. They are initialized to
   // the default implementations above.
   ClockInterface* clock_;
-  ConnectionManager* connection_manager_;
+  ConnectionManagerInterface* connection_manager_;
   HardwareInterface* hardware_;
   MetricsLibraryInterface* metrics_lib_;
   PrefsInterface* prefs_;
diff --git a/mock_connection_manager.h b/mock_connection_manager.h
index 9530865..609b51d 100644
--- a/mock_connection_manager.h
+++ b/mock_connection_manager.h
@@ -7,17 +7,16 @@
 
 #include <gmock/gmock.h>
 
-#include "update_engine/connection_manager.h"
+#include "update_engine/connection_manager_interface.h"
 
 namespace chromeos_update_engine {
 
 // This class mocks the generic interface to the connection manager
 // (e.g FlimFlam, Shill, etc.) to consolidate all connection-related
 // logic in update_engine.
-class MockConnectionManager : public ConnectionManager {
+class MockConnectionManager : public ConnectionManagerInterface {
  public:
-  explicit MockConnectionManager(SystemState* system_state)
-      : ConnectionManager(system_state) {}
+  MockConnectionManager() = default;
 
   MOCK_CONST_METHOD3(GetConnectionProperties,
                      bool(DBusWrapperInterface* dbus_iface,
@@ -26,12 +25,6 @@
 
   MOCK_CONST_METHOD2(IsUpdateAllowedOver, bool(NetworkConnectionType type,
                                                NetworkTethering tethering));
-
-  MOCK_CONST_METHOD1(StringForConnectionType,
-      const char*(NetworkConnectionType type));
-
-  MOCK_CONST_METHOD1(StringForTethering,
-      const char*(NetworkTethering tethering));
 };
 
 }  // namespace chromeos_update_engine
diff --git a/mock_http_fetcher.h b/mock_http_fetcher.h
index 89f5d21..36b6a1d 100644
--- a/mock_http_fetcher.h
+++ b/mock_http_fetcher.h
@@ -40,8 +40,7 @@
         timeout_id_(chromeos::MessageLoop::kTaskIdNull),
         paused_(false),
         fail_transfer_(false),
-        never_use_(false),
-        mock_connection_manager_(&fake_system_state_) {
+        never_use_(false) {
     fake_system_state_.set_connection_manager(&mock_connection_manager_);
     data_.insert(data_.end(), data, data + size);
   }
diff --git a/omaha_request_action.cc b/omaha_request_action.cc
index dff8ad3..2f361e5 100644
--- a/omaha_request_action.cc
+++ b/omaha_request_action.cc
@@ -21,6 +21,7 @@
 #include <expat.h>
 
 #include "update_engine/action_pipe.h"
+#include "update_engine/connection_manager.h"
 #include "update_engine/constants.h"
 #include "update_engine/hardware_interface.h"
 #include "update_engine/omaha_hash_calculator.h"
@@ -1448,7 +1449,8 @@
   NetworkConnectionType type;
   NetworkTethering tethering;
   RealDBusWrapper dbus_iface;
-  ConnectionManager* connection_manager = system_state_->connection_manager();
+  ConnectionManagerInterface* connection_manager =
+      system_state_->connection_manager();
   if (!connection_manager->GetConnectionProperties(&dbus_iface,
                                                    &type, &tethering)) {
     LOG(INFO) << "We could not determine our connection type. "
@@ -1457,7 +1459,7 @@
   }
   bool is_allowed = connection_manager->IsUpdateAllowedOver(type, tethering);
   LOG(INFO) << "We are connected via "
-            << connection_manager->StringForConnectionType(type)
+            << ConnectionManager::StringForConnectionType(type)
             << ", Updates allowed: " << (is_allowed ? "Yes" : "No");
   return is_allowed;
 }
diff --git a/omaha_request_action_unittest.cc b/omaha_request_action_unittest.cc
index 8f4dc87..5b8fba9 100644
--- a/omaha_request_action_unittest.cc
+++ b/omaha_request_action_unittest.cc
@@ -445,7 +445,7 @@
   OmahaResponse response;
   // Set up a connection manager that doesn't allow a valid update over
   // the current ethernet connection.
-  MockConnectionManager mock_cm(nullptr);
+  MockConnectionManager mock_cm;
   fake_system_state_.set_connection_manager(&mock_cm);
 
   EXPECT_CALL(mock_cm, GetConnectionProperties(_, _, _)).WillRepeatedly(
@@ -454,9 +454,6 @@
           Return(true)));
   EXPECT_CALL(mock_cm, IsUpdateAllowedOver(NetworkConnectionType::kEthernet, _))
     .WillRepeatedly(Return(false));
-  EXPECT_CALL(mock_cm,
-              StringForConnectionType(NetworkConnectionType::kEthernet))
-    .WillRepeatedly(Return(shill::kTypeEthernet));
 
   ASSERT_FALSE(
       TestUpdateCheck(nullptr,  // request_params
diff --git a/omaha_response_handler_action.cc b/omaha_response_handler_action.cc
index 67639cc..6c7c166 100644
--- a/omaha_response_handler_action.cc
+++ b/omaha_response_handler_action.cc
@@ -10,7 +10,7 @@
 #include <base/strings/string_util.h>
 #include <policy/device_policy.h>
 
-#include "update_engine/connection_manager.h"
+#include "update_engine/connection_manager_interface.h"
 #include "update_engine/constants.h"
 #include "update_engine/delta_performer.h"
 #include "update_engine/hardware_interface.h"
diff --git a/payload_state.cc b/payload_state.cc
index ed7b775..a15d68b 100644
--- a/payload_state.cc
+++ b/payload_state.cc
@@ -10,7 +10,6 @@
 #include <base/logging.h>
 #include <base/strings/string_util.h>
 #include <base/strings/stringprintf.h>
-#include <base/format_macros.h>
 #include <policy/device_policy.h>
 
 #include "update_engine/clock.h"
@@ -176,7 +175,8 @@
   NetworkConnectionType network_connection_type;
   NetworkTethering tethering;
   RealDBusWrapper dbus_iface;
-  ConnectionManager* connection_manager = system_state_->connection_manager();
+  ConnectionManagerInterface* connection_manager =
+      system_state_->connection_manager();
   if (!connection_manager->GetConnectionProperties(&dbus_iface,
                                                    &network_connection_type,
                                                    &tethering)) {
diff --git a/real_system_state.h b/real_system_state.h
index 7e0c16d..4e97b95 100644
--- a/real_system_state.h
+++ b/real_system_state.h
@@ -47,7 +47,7 @@
 
   inline ClockInterface* clock() override { return &clock_; }
 
-  inline ConnectionManager* connection_manager() override {
+  inline ConnectionManagerInterface* connection_manager() override {
     return &connection_manager_;
   }
 
diff --git a/system_state.h b/system_state.h
index 21aeabd..65d4e48 100644
--- a/system_state.h
+++ b/system_state.h
@@ -25,7 +25,7 @@
 // any circular references in header file inclusion. Hence forward-declaring
 // the required classes.
 class ClockInterface;
-class ConnectionManager;
+class ConnectionManagerInterface;
 class GpioHandler;
 class HardwareInterface;
 class OmahaRequestParams;
@@ -54,7 +54,7 @@
   virtual ClockInterface* clock() = 0;
 
   // Gets the connection manager object.
-  virtual ConnectionManager* connection_manager() = 0;
+  virtual ConnectionManagerInterface* connection_manager() = 0;
 
   // Gets the hardware interface object.
   virtual HardwareInterface* hardware() = 0;
diff --git a/update_attempter_unittest.cc b/update_attempter_unittest.cc
index 8c6fa3d..07ba451 100644
--- a/update_attempter_unittest.cc
+++ b/update_attempter_unittest.cc
@@ -100,7 +100,6 @@
  protected:
   UpdateAttempterTest()
       : attempter_(&fake_system_state_, &dbus_),
-        mock_connection_manager(&fake_system_state_),
         fake_dbus_system_bus_(reinterpret_cast<DBusGConnection*>(1)),
         fake_dbus_debugd_proxy_(reinterpret_cast<DBusGProxy*>(2)) {
     // Override system state members.
diff --git a/utils.h b/utils.h
index b661b43..73d6eb9 100644
--- a/utils.h
+++ b/utils.h
@@ -18,13 +18,13 @@
 #include <base/files/file_path.h>
 #include <base/posix/eintr_wrapper.h>
 #include <base/time/time.h>
-#include <chromeos/secure_blob.h>
 #include <chromeos/key_value_store.h>
+#include <chromeos/secure_blob.h>
 #include "metrics/metrics_library.h"
 
 #include "update_engine/action.h"
 #include "update_engine/action_processor.h"
-#include "update_engine/connection_manager.h"
+#include "update_engine/connection_manager_interface.h"
 #include "update_engine/constants.h"
 #include "update_engine/file_descriptor.h"
 #include "update_engine/metrics.h"