Create a FakeTetherService, which stubs out TetherService for development.

chrome/browser/chromeos/tether/tether_service.cc

 // Copyright 2017 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 "chrome/browser/chromeos/tether/tether_service.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "chrome/browser/chromeos/net/tether_notification_presenter.h"
 #include "chrome/browser/chromeos/tether/tether_service_factory.h"
 #include "chrome/browser/cryptauth/chrome_cryptauth_service_factory.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/signin/profile_oauth2_token_service_factory.h"
 #include "chrome/common/pref_names.h"
 #include "chromeos/chromeos_switches.h"
 #include "chromeos/components/tether/initializer.h"
 #include "chromeos/network/network_connect.h"
 #include "chromeos/network/network_type_pattern.h"
 #include "components/cryptauth/cryptauth_service.h"
 #include "components/prefs/pref_registry_simple.h"
 #include "components/prefs/pref_service.h"
 #include "device/bluetooth/bluetooth_adapter_factory.h"
 #include "ui/message_center/message_center.h"
 
 // static
 TetherService* TetherService::Get(Profile* profile) {
-  return TetherServiceFactory::GetForBrowserContext(profile);
+  if (IsFeatureFlagEnabled())
+    return TetherServiceFactory::GetForBrowserContext(profile);
+
+  return nullptr;
 }
 
 // static
 void TetherService::RegisterProfilePrefs(PrefRegistrySimple* registry) {
   registry->RegisterBooleanPref(prefs::kInstantTetheringAllowed, true);
   registry->RegisterBooleanPref(prefs::kInstantTetheringEnabled, true);
   chromeos::tether::Initializer::RegisterProfilePrefs(registry);
 }
 
+// static
+bool TetherService::IsFeatureFlagEnabled() {
+  return base::CommandLine::ForCurrentProcess()->HasSwitch(
+      chromeos::switches::kEnableTether);
+}
+
 TetherService::TetherService(
     Profile* profile,
     chromeos::PowerManagerClient* power_manager_client,
     chromeos::SessionManagerClient* session_manager_client,
     cryptauth::CryptAuthService* cryptauth_service,
     chromeos::NetworkStateHandler* network_state_handler)
     : profile_(profile),
       power_manager_client_(power_manager_client),
       session_manager_client_(session_manager_client),
       cryptauth_service_(cryptauth_service),
@@ skipping 120 matching lines @@
     profile_->GetPrefs()->SetBoolean(prefs::kInstantTetheringEnabled,
                                      is_enabled);
     UpdateTetherTechnologyState();
   }
 }
 
 void TetherService::OnPrefsChanged() {
   UpdateTetherTechnologyState();
 }
 
+bool TetherService::HasSyncedTetherHosts() const {
+  return !cryptauth_service_->GetCryptAuthDeviceManager()
+              ->GetTetherHosts()
+              .empty();
+}
+
 void TetherService::UpdateTetherTechnologyState() {
   chromeos::NetworkStateHandler::TechnologyState tether_technology_state =
       GetTetherTechnologyState();
 
   network_state_handler_->SetTetherTechnologyState(tether_technology_state);
 
   if (tether_technology_state ==
       chromeos::NetworkStateHandler::TechnologyState::TECHNOLOGY_ENABLED) {
     StartTetherIfEnabled();
   } else {
     StopTether();
   }
 }
 
 chromeos::NetworkStateHandler::TechnologyState
 TetherService::GetTetherTechnologyState() {
   if (shut_down_ || suspended_ || session_manager_client_->IsScreenLocked() ||
-      !IsFeatureFlagEnabled() || !HasSyncedTetherHosts()) {
+      !HasSyncedTetherHosts()) {
     return chromeos::NetworkStateHandler::TechnologyState::
         TECHNOLOGY_UNAVAILABLE;
   } else if (!IsAllowedByPolicy()) {
     return chromeos::NetworkStateHandler::TechnologyState::
         TECHNOLOGY_PROHIBITED;
   } else if (!IsBluetoothAvailable()) {
     // TODO (hansberry): This unfortunately results in a weird UI state for
     // Settings where the toggle is clickable but immediately becomes disabled
     // after enabling it. Possible solution: grey out the toggle and tell the
     // user to turn Bluetooth on?
     return chromeos::NetworkStateHandler::TechnologyState::
         TECHNOLOGY_UNINITIALIZED;
   } else if (!IsEnabledbyPreference()) {
     return chromeos::NetworkStateHandler::TechnologyState::TECHNOLOGY_AVAILABLE;
   }
 
   return chromeos::NetworkStateHandler::TechnologyState::TECHNOLOGY_ENABLED;
 }
 
 void TetherService::OnBluetoothAdapterFetched(
     scoped_refptr<device::BluetoothAdapter> adapter) {
   adapter_ = adapter;
   adapter_->AddObserver(this);
   UpdateTetherTechnologyState();
 }
 
-bool TetherService::HasSyncedTetherHosts() const {
-  return !cryptauth_service_->GetCryptAuthDeviceManager()
-              ->GetTetherHosts()
-              .empty();
-}
-
-bool TetherService::IsFeatureFlagEnabled() const {
-  return base::CommandLine::ForCurrentProcess()->HasSwitch(
-      chromeos::switches::kEnableTether);
-}
-
 bool TetherService::IsBluetoothAvailable() const {
   return adapter_.get() && adapter_->IsPresent() && adapter_->IsPowered();
 }
 
 bool TetherService::IsAllowedByPolicy() const {
   return profile_->GetPrefs()->GetBoolean(prefs::kInstantTetheringAllowed);
 }
 
 bool TetherService::IsEnabledbyPreference() const {
   return profile_->GetPrefs()->GetBoolean(prefs::kInstantTetheringEnabled);
 }