Add a new app API to enable watchdog behavior restarts in kiosk apps

extensions/browser/api/runtime/runtime_api.h

 // Copyright 2014 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.
 
 #ifndef EXTENSIONS_BROWSER_API_RUNTIME_RUNTIME_API_H_
 #define EXTENSIONS_BROWSER_API_RUNTIME_RUNTIME_API_H_
 
 #include <string>
 
 #include "base/macros.h"
 #include "base/scoped_observer.h"
+#include "base/time/time.h"
+#include "base/timer/timer.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 #include "extensions/browser/api/runtime/runtime_api_delegate.h"
 #include "extensions/browser/browser_context_keyed_api_factory.h"
 #include "extensions/browser/extension_function.h"
 #include "extensions/browser/extension_registry_observer.h"
 #include "extensions/browser/process_manager.h"
 #include "extensions/browser/process_manager_observer.h"
 #include "extensions/browser/update_observer.h"
 #include "extensions/common/api/runtime.h"
 
 namespace base {
 class Version;
 }
 
 namespace content {
 class BrowserContext;
 }
 
+class PrefRegistrySimple;
+
 namespace extensions {
 
 namespace api {
 namespace runtime {
 struct PlatformInfo;
 }
 }
 
 class Extension;
 class ExtensionHost;
 class ExtensionRegistry;
 
 // Runtime API dispatches onStartup, onInstalled, and similar events to
 // extensions. There is one instance shared between a browser context and
 // its related incognito instance.
 class RuntimeAPI : public BrowserContextKeyedAPI,
                    public content::NotificationObserver,
                    public ExtensionRegistryObserver,
                    public UpdateObserver,
                    public ProcessManagerObserver {
  public:
+  // The status of the restart on watchdog request.
+  enum class RestartOnWatchdogStatus {
+    // The request was made by a different extension other than the first one to
+    // invoke the restartOnWatchdog runtime API.
+    FAILED_NOT_FIRST_EXTENSION,
+
+    // The request came too soon after a previous restart induced by the
+    // watchdog API. It failed to be scheduled as requested, and was instead
+    // throttled.
+    FAILED_THROTTLED,
+
+    // Any previously scheduled restart was successfully canceled.
+    SUCCESS_RESTART_CANCELED,
+
+    // A restart was successfully scheduled.
+    SUCCESS_RESTART_SCHEDULED,
+  };
+
   static BrowserContextKeyedAPIFactory<RuntimeAPI>* GetFactoryInstance();
 
+  static void RegisterPrefs(PrefRegistrySimple* registry);
+
   explicit RuntimeAPI(content::BrowserContext* context);
   ~RuntimeAPI() override;
 
   // content::NotificationObserver overrides:
   void Observe(int type,
                const content::NotificationSource& source,
                const content::NotificationDetails& details) override;
 
   void ReloadExtension(const std::string& extension_id);
   bool CheckForUpdates(const std::string& extension_id,
                        const RuntimeAPIDelegate::UpdateCheckCallback& callback);
   void OpenURL(const GURL& uninstall_url);
   bool GetPlatformInfo(api::runtime::PlatformInfo* info);
   bool RestartDevice(std::string* error_message);
+
+  RestartOnWatchdogStatus RestartDeviceOnWatchdogTimeout(
+      const std::string& extension_id,
+      int seconds_from_now);
+
   bool OpenOptionsPage(const Extension* extension);
 
  private:
   friend class BrowserContextKeyedAPIFactory<RuntimeAPI>;
+  friend class RestartAfterDelayApiTest;
 
   // ExtensionRegistryObserver implementation.
   void OnExtensionLoaded(content::BrowserContext* browser_context,
                          const Extension* extension) override;
   void OnExtensionWillBeInstalled(content::BrowserContext* browser_context,
                                   const Extension* extension,
                                   bool is_update,
                                   const std::string& old_name) override;
   void OnExtensionUninstalled(content::BrowserContext* browser_context,
                               const Extension* extension,
                               UninstallReason reason) override;
 
+  // Cancels any previously scheduled restart request.
+  void MaybeCancelRunningWatchdogTimer();
+
+  RestartOnWatchdogStatus ScheduleDelayedRestart(const base::Time& now,
+                                                 int seconds_from_now,
+                                                 double stored_last_restart);
+
+  // Called when the restart watchdog timer times out so that it attempts to
+  // execute the restart request scheduled earlier.
+  void OnRestartWatchdogTimeout();
+
+  // Called when the host device is being shutdown or restarted.
+  void OnDeviceShutdown();
+
   // BrowserContextKeyedAPI implementation:
   static const char* service_name() { return "RuntimeAPI"; }
   static const bool kServiceRedirectedInIncognito = true;
   static const bool kServiceIsNULLWhileTesting = true;
   void Shutdown() override;
 
   // extensions::UpdateObserver overrides:
   void OnAppUpdateAvailable(const Extension* extension) override;
   void OnChromeUpdateAvailable() override;
 
   // ProcessManagerObserver implementation:
   void OnBackgroundHostStartup(const Extension* extension) override;
 
   // Pref related functions that deals with info about installed extensions that
   // has not been loaded yet.
   // Used to send chrome.runtime.onInstalled event upon loading the extensions.
   bool ReadPendingOnInstallInfoFromPref(const ExtensionId& extension_id,
                                         base::Version* previous_version);
   void RemovePendingOnInstallInfoFromPref(const ExtensionId& extension_id);
   void StorePendingOnInstallInfoToPref(const Extension* extension);
 
+  void AllowNonKiostAppsInRestartOnWatchdogForTesting();
+
+  void set_min_duration_between_restarts_for_testing(base::TimeDelta delta) {
+    minimum_duration_between_restarts_ = delta;
+  }
+
   std::unique_ptr<RuntimeAPIDelegate> delegate_;
 
   content::BrowserContext* browser_context_;
 
-  // True if we should dispatch the chrome.runtime.onInstalled event with

[Devlin, 2016/06/10 00:34:45]

What's the reason for moving this?

[afakhry, 2016/06/13 14:46:00]

I'm sure you know this, and probably would think it's unnecessary, but the
reason is alignment and padding. It's really bad to have a less alignment
restrictive type objects in the middle of more restrictive ones.

Assuming Linux and 64-bit architecture:
bool is 1 byte ---> alignment requirement is 1 byte (so can be allocated in any
address).

The previous member |browser_context_| is a pointer. Pointers on 64-bit machines
are 8 bytes. ---> alignment requirements is 8 bytes.

The following member |registrar_| has only one member of type std::vector<>.
While the implementation of std::vector may vary, but let's assume the one I
have locally in /usr/include/. It has three pinters:
	pointer _M_start;
	pointer _M_finish;
	pointer _M_end_of_storage;

Again 8 byte aligned. Let's roughly sketch the memory layout:

+---+---+---+---+---+---+---+---+
|   |   |   |   |   |   |   |   |
|<----- browser_context_ ------>|
|   |   |   |   |   |   |   |   |
+---+---+---+---+---+---+---+---+
|   | X | X | X | X | X | X | X |
| b | X | X | X | X | X | X | X |
|   | X | X | X | X | X | X | X |
+---+---+---+---+---+---+---+---+
|   |   |   |   |   |   |   |   |
|<--------- _M_start ---------->|
|   |   |   |   |   |   |   |   |
+---+---+---+---+---+---+---+---+
|   |   |   |   |   |   |   |   |
|<--------- _M_finish --------->|
|   |   |   |   |   |   |   |   |
+---+---+---+---+---+---+---+---+
|   |   |   |   |   |   |   |   |
|<---- _M_end_of_storage ------>|
|   |   |   |   |   |   |   |   |
+---+---+---+---+---+---+---+---+

'b' is our bool |dispatch_chrome_updated_event_|, and the X's are useless
padding bytes. 

So I moved it to the end and placed our two new bools after it, in order to fill
two of those padding bytes. 

I could have just placed the new bools after |dispatch_chrome_updated_event_|
while it was still up here, but I have this personal preference of having the
bools at the end of the object.

I didn't want our new bools to introduce extra new padding bytes.

[Devlin, 2016/06/13 15:54:57]

Realistically, since this is a singleton per profile, it's probably never gonna
matter, but I'm not going to stand in the way of minor optimizations :)  Thanks
for the detailed answer!

-  // reason "chrome_update" upon loading each extension.
-  bool dispatch_chrome_updated_event_;
-
   content::NotificationRegistrar registrar_;
 
   // Listen to extension notifications.
   ScopedObserver<ExtensionRegistry, ExtensionRegistryObserver>
       extension_registry_observer_;
   ScopedObserver<ProcessManager, ProcessManagerObserver>
       process_manager_observer_;
 
+  // The ID of the first extension to call the restartOnWatchdog API. Any other
+  // extensions to call this API after that will fail.
+  std::string schedule_restart_first_extension_id_;
+
+  // The timer that will trigger a device restart when it times out.
+  base::OneShotTimer watchdog_timer_;
+
+  // The minimum allowed duration between two successive restarts on watchdog
+  // timer.
+  base::TimeDelta minimum_duration_between_restarts_;
+
+  // True if we should dispatch the chrome.runtime.onInstalled event with
+  // reason "chrome_update" upon loading each extension.
+  bool dispatch_chrome_updated_event_ = false;

[Devlin, 2016/06/10 00:34:45]

Let's not mix initialization styles.  Since we initialize other members (like
browser_context_) in the ctor, we should do that with these, too.

[afakhry, 2016/06/13 14:46:00]

Done.

+
+  // The currently expected restarts induced by this API.
+  // chrome.runtime.restartAfterDelay() introduces a watchdog expected restart.
+  // chrome.runtime.restart() introduces a non-watchdog expected restart.
+  bool expecting_watchdog_restart_ = false;
+  bool expecting_non_watchdog_restart_ = false;
+
+  base::WeakPtrFactory<RuntimeAPI> weak_ptr_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(RuntimeAPI);
 };
 
 template <>
 void BrowserContextKeyedAPIFactory<RuntimeAPI>::DeclareFactoryDependencies();
 
 class RuntimeEventRouter {
  public:
   // Dispatches the onStartup event to all currently-loaded extensions.
   static void DispatchOnStartupEvent(content::BrowserContext* context,
@@ skipping 82 matching lines @@
 
 class RuntimeRestartFunction : public UIThreadExtensionFunction {
  public:
   DECLARE_EXTENSION_FUNCTION("runtime.restart", RUNTIME_RESTART)
 
  protected:
   ~RuntimeRestartFunction() override {}
   ResponseAction Run() override;
 };
 
+class RuntimeRestartAfterDelayFunction : public UIThreadExtensionFunction {
+ public:
+  DECLARE_EXTENSION_FUNCTION("runtime.restartAfterDelay",
+                             RUNTIME_RESTARTAFTERDELAY)
+
+ protected:
+  ~RuntimeRestartAfterDelayFunction() override {}
+  ResponseAction Run() override;
+};
+
 class RuntimeGetPlatformInfoFunction : public UIThreadExtensionFunction {
  public:
   DECLARE_EXTENSION_FUNCTION("runtime.getPlatformInfo",
                              RUNTIME_GETPLATFORMINFO);
 
  protected:
   ~RuntimeGetPlatformInfoFunction() override {}
   ResponseAction Run() override;
 };
 
 class RuntimeGetPackageDirectoryEntryFunction
     : public UIThreadExtensionFunction {
  public:
   DECLARE_EXTENSION_FUNCTION("runtime.getPackageDirectoryEntry",
                              RUNTIME_GETPACKAGEDIRECTORYENTRY)
 
  protected:
   ~RuntimeGetPackageDirectoryEntryFunction() override {}
   ResponseAction Run() override;
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_API_RUNTIME_RUNTIME_API_H_