It's going to be removed from Chromium, see https://crbug.com/812523.

/cc @electron/code-owners 
shell/browser/api/electron_api_app.h
bool RequestSingleInstanceLock();
  void ReleaseSingleInstanceLock();
  bool Relaunch(gin_helper::Arguments* args);
  void DisableHardwareAcceleration(gin_helper::ErrorThrower thrower);
  void DisableDomainBlockingFor3DAPIs(gin_helper::ErrorThrower thrower);
  bool IsAccessibilitySupportEnabled();
  void SetAccessibilitySupportEnabled(gin_helper::ErrorThrower thrower,
                                      bool enabled);
  Browser::LoginItemSettings GetLoginItemSettings(gin_helper::Arguments* args);
#if defined(USE_NSS_CERTS)
  void ImportCertificate(const base::DictionaryValue& options,
                         net::CompletionRepeatingCallback callback);
#endif
  v8::Local<v8::Promise> GetFileIcon(const base::FilePath& path,
                                     gin_helper::Arguments* args);
  std::vector<gin_helper::Dictionary> GetAppMetrics(v8::Isolate* isolate);
  v8::Local<v8::Value> GetGPUFeatureStatus(v8::Isolate* isolate);
  v8::Local<v8::Promise> GetGPUInfo(v8::Isolate* isolate,
                                    const std::string& info_type);
  void EnableSandbox(gin_helper::ErrorThrower thrower);
  void SetUserAgentFallback(const std::string& user_agent);
  std::string GetUserAgentFallback();
  void SetBrowserClientCanUseCustomSiteInstance(bool should_disable);
  bool CanBrowserClientUseCustomSiteInstance();
#if defined(OS_MACOSX)
  void SetActivationPolicy(gin_helper::ErrorThrower thrower,
                           const std::string& policy);
  bool MoveToApplicationsFolder(gin_helper::ErrorThrower, gin::Arguments* args);
  bool IsInApplicationsFolder();
  v8::Local<v8::Value> GetDockAPI(v8::Isolate* isolate);