Add unit test for the Settings API Bubble.

chrome/browser/extensions/api/settings_overrides/settings_overrides_api.cc

 // Copyright 2013 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/extensions/api/settings_overrides/settings_overrides_api.h"
 
 #include "base/lazy_instance.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/extensions/api/preference/preference_api.h"
@@ skipping 93 matching lines @@
 }
 
 BrowserContextKeyedAPIFactory<SettingsOverridesAPI>*
 SettingsOverridesAPI::GetFactoryInstance() {
   return g_factory.Pointer();
 }
 
 void SettingsOverridesAPI::SetPref(const std::string& extension_id,
                                    const std::string& pref_key,
                                    base::Value* value) {
-  PreferenceAPI::Get(profile_)->SetExtensionControlledPref(
-      extension_id,
-      pref_key,
-      kExtensionPrefsScopeRegular,
-      value);
+  PreferenceAPI* prefs = PreferenceAPI::Get(profile_);
+  if (!prefs)
+    return;  // Expected in unit tests.
+  prefs->SetExtensionControlledPref(extension_id,
+                                    pref_key,
+                                    kExtensionPrefsScopeRegular,
+                                    value);
 }
 
 void SettingsOverridesAPI::UnsetPref(const std::string& extension_id,
                                      const std::string& pref_key) {
-  PreferenceAPI::Get(profile_)->RemoveExtensionControlledPref(
+  PreferenceAPI* prefs = PreferenceAPI::Get(profile_);
+  if (!prefs)
+    return;  // Expected in unit tests.
+  prefs->RemoveExtensionControlledPref(
       extension_id,
       pref_key,
       kExtensionPrefsScopeRegular);
 }
 
 void SettingsOverridesAPI::Observe(
     int type,
     const content::NotificationSource& source,
     const content::NotificationDetails& details) {
   switch (type) {
@@ skipping 112 matching lines @@
 
 template <>
 void BrowserContextKeyedAPIFactory<
     SettingsOverridesAPI>::DeclareFactoryDependencies() {
   DependsOn(ExtensionPrefsFactory::GetInstance());
   DependsOn(PreferenceAPI::GetFactoryInstance());
   DependsOn(TemplateURLServiceFactory::GetInstance());
 }
 
 }  // namespace extensions