Show a notification when an ephemeral app consumes excessive disk space

chrome/browser/extensions/extension_storage_monitor.cc

Index: chrome/browser/extensions/extension_storage_monitor.cc
diff --git a/chrome/browser/extensions/extension_storage_monitor.cc b/chrome/browser/extensions/extension_storage_monitor.cc
new file mode 100644
index 0000000000000000000000000000000000000000..9376aebdf388967a697c49203da5d635b96268fa
--- /dev/null
+++ b/chrome/browser/extensions/extension_storage_monitor.cc
@@ -0,0 +1,406 @@
+// 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.
+
+#include "chrome/browser/extensions/extension_storage_monitor.h"
+
+#include <map>
+
+#include "base/strings/string_number_conversions.h"
+#include "base/strings/utf_string_conversions.h"
+#include "chrome/browser/chrome_notification_types.h"
+#include "chrome/browser/extensions/extension_storage_monitor_factory.h"
+#include "chrome/browser/extensions/extension_util.h"
+#include "chrome/browser/extensions/image_loader.h"
+#include "chrome/common/extensions/manifest_handlers/app_launch_info.h"
+#include "chrome/common/extensions/manifest_handlers/icons_handler.h"
+#include "content/public/browser/browser_context.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/browser/notification_details.h"
+#include "content/public/browser/notification_source.h"
+#include "content/public/browser/storage_partition.h"
+#include "extensions/browser/extension_prefs.h"
+#include "extensions/browser/extension_registry.h"
+#include "extensions/common/extension.h"
+#include "extensions/common/extension_resource.h"
+#include "grit/generated_resources.h"
+#include "ui/base/l10n/l10n_util.h"
+#include "ui/message_center/message_center.h"
+#include "ui/message_center/notifier_settings.h"
+#include "webkit/browser/quota/quota_manager.h"
+#include "webkit/browser/quota/storage_observer.h"
+
+using content::BrowserThread;
+
+namespace extensions {
+
+namespace {
+
+// The rate at which we would like to observe storage events.
+const int kStorageEventRateSec = 30;
+
+// The storage type to monitor.
+const quota::StorageType kMonitorStorageType = quota::kStorageTypePersistent;
+
+// Set the thresholds for the first notification. Ephemeral apps have a lower
+// threshold than installed extensions and apps. Once a threshold is exceeded,
+// it will be doubled to throttle notifications.
+const int64 kMBytes = 1024 * 1024;
+const int64 kEphemeralAppInitialThreshold = 250 * kMBytes;
+const int64 kExtensionInitialThreshold = 1000 * kMBytes;
+
+// Notifications have an ID so that we can update them.
+const char kNotificationIdPrefix[] = "ExtensionStorageMonitor_";
+const char kSystemNotifierId[] = "ExtensionStorageMonitor";
+
+}  // namespace
+
+// StorageEventObserver monitors the storage usage of extensions and lives on
+// the IO thread. When a threshold is exceeded, a message will be posted to the
+// UI thread, which displays the notification.
+class StorageEventObserver
+    : public base::RefCountedThreadSafe<
+          StorageEventObserver,
+          BrowserThread::DeleteOnIOThread>,
+      public quota::StorageObserver {
+ public:
+  explicit StorageEventObserver(
+      base::WeakPtr<ExtensionStorageMonitor> storage_monitor)
+      : storage_monitor_(storage_monitor) {
+  }
+
+  // Register as an observer for the extension's storage events.
+  void StartObservingForExtension(
+      scoped_refptr<quota::QuotaManager> quota_manager,
+      const std::string& extension_id,
+      const GURL& site_url,
+      int64 next_threshold,
+      int rate) {
+    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+    DCHECK(quota_manager.get());
+
+    GURL origin = site_url.GetOrigin();
+    StorageState& state = origin_state_map_[origin];
+    state.quota_manager = quota_manager;
+    state.extension_id = extension_id;
+    state.next_threshold = next_threshold;
+
+    quota::StorageObserver::MonitorParams params(
+        kMonitorStorageType,
+        origin,
+        base::TimeDelta::FromSeconds(rate),
+        false);
+    quota_manager->AddStorageObserver(this, params);
+  }
+
+  // Deregister as an observer for the extension's storage events.
+  void StopObservingForExtension(const std::string& extension_id) {
+    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+
+    for (OriginStorageStateMap::iterator it = origin_state_map_.begin();
+         it != origin_state_map_.end(); ) {
+      if (it->second.extension_id == extension_id) {
+        quota::StorageObserver::Filter filter(kMonitorStorageType, it->first);
+        it->second.quota_manager->RemoveStorageObserverForFilter(this, filter);
+        origin_state_map_.erase(it++);

[koz (OOO until 15th September), 2014/04/07 05:24:32]

Can it++ not go in the for-part?

[tmdiep, 2014/04/07 08:45:01]

I need the return value of the post-increment operator to erase the current
element, while  advancing the iterator so that it remains valid (idiom for
erasing map elements in a loop).

[koz (OOO until 15th September), 2014/04/08 00:26:00]

Ah, I see. Very cool :-)

+      } else {
+        ++it;
+      }
+    }
+  }
+
+  // Stop observing all storage events. Called during shutdown.
+  void StopObserving() {
+    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+
+    for (OriginStorageStateMap::iterator it = origin_state_map_.begin();
+         it != origin_state_map_.end(); ++it) {
+      it->second.quota_manager->RemoveStorageObserver(this);
+    }
+    origin_state_map_.clear();
+  }
+
+ private:
+  friend class base::DeleteHelper<StorageEventObserver>;
+  friend struct content::BrowserThread::DeleteOnThread<
+      content::BrowserThread::IO>;
+
+  struct StorageState {
+    scoped_refptr<quota::QuotaManager> quota_manager;
+    std::string extension_id;
+    int64 next_threshold;
+
+    StorageState() : next_threshold(0) {}
+  };
+  typedef std::map<GURL, StorageState> OriginStorageStateMap;
+
+  virtual ~StorageEventObserver() {
+    // The observers should have been cleared by now, but double-check before
+    // destruction.

[koz (OOO until 15th September), 2014/04/07 05:24:32]

nit: Replace comment with DCHECK(origin_state_map_.empty()) ?

[tmdiep, 2014/04/07 08:45:01]

Done.

+    StopObserving();
+  }
+
+  // quota::StorageObserver implementation.
+  virtual void OnStorageEvent(const Event& event) OVERRIDE {
+    OriginStorageStateMap::iterator state =
+        origin_state_map_.find(event.filter.origin);
+    if (state == origin_state_map_.end())
+      return;
+
+    if (event.usage >= state->second.next_threshold) {
+      while (event.usage >= state->second.next_threshold)
+        state->second.next_threshold *= 2;
+
+      BrowserThread::PostTask(
+          BrowserThread::UI,
+          FROM_HERE,
+          base::Bind(&ExtensionStorageMonitor::OnStorageThresholdExceeded,
+                     storage_monitor_,
+                     state->second.extension_id,
+                     state->second.next_threshold,
+                     event.usage));
+    }
+  }
+
+  OriginStorageStateMap origin_state_map_;
+  base::WeakPtr<ExtensionStorageMonitor> storage_monitor_;
+};
+
+// ExtensionStorageMonitor
+
+// static
+ExtensionStorageMonitor* ExtensionStorageMonitor::Get(
+    content::BrowserContext* context) {
+  return ExtensionStorageMonitorFactory::GetForBrowserContext(context);
+}
+
+ExtensionStorageMonitor::ExtensionStorageMonitor(
+    content::BrowserContext* context)
+    : enable_for_all_extensions_(false),
+      initial_extension_threshold_(kExtensionInitialThreshold),
+      initial_ephemeral_threshold_(kEphemeralAppInitialThreshold),
+      observer_rate_(kStorageEventRateSec),
+      context_(context),
+      weak_ptr_factory_(this) {
+  registrar_.Add(this, chrome::NOTIFICATION_EXTENSION_LOADED,
+                 content::Source<content::BrowserContext>(context_));
+  registrar_.Add(this, chrome::NOTIFICATION_PROFILE_DESTROYED,
+                 content::Source<content::BrowserContext>(context_));
+
+  ExtensionRegistry* registry = ExtensionRegistry::Get(context_);
+  DCHECK(registry);
+  registry->AddObserver(this);
+}
+
+ExtensionStorageMonitor::~ExtensionStorageMonitor() {}
+
+void ExtensionStorageMonitor::Observe(
+    int type,
+    const content::NotificationSource& source,
+    const content::NotificationDetails& details) {
+  switch (type) {
+    case chrome::NOTIFICATION_EXTENSION_LOADED: {
+      const Extension* extension =
+          content::Details<const Extension>(details).ptr();
+      StartMonitoringStorage(extension);
+      break;
+    }
+    case chrome::NOTIFICATION_PROFILE_DESTROYED: {
+      StopMonitoringAll();

[koz (OOO until 15th September), 2014/04/07 05:24:32]

Should this also clear any notifications that are currently being shown to the
user? It might be worth considering using RAII for the currently shown
notifications. That would mean representing each currently shown notification as
an object and storing it in a map of linked_ptr<>s.

[tmdiep, 2014/04/07 08:45:01]

Hmm, yes clearing the notifications would be a good idea. I don't think we need
to go as far as RAII for this though, can just save a list of extension ids.

+      break;
+    }
+    default:
+      NOTREACHED();
+  };
+}
+
+void ExtensionStorageMonitor::OnExtensionUnloaded(const Extension* extension) {
+  DCHECK(extension);
+  StopMonitoringStorage(extension->id());

[koz (OOO until 15th September), 2014/04/07 05:24:32]

Same as above: when an extension gets unloaded, should we clear its
notifications?

[tmdiep, 2014/04/07 08:45:01]

I removed the notification on uninstall. Unloading also occurs when the
extension is disabled. In future patches there will be additional actions, such
as capping quota and clearing data, which are applicable when disabled, so we
might want to keep the notification around.

+}
+
+// static
+std::string ExtensionStorageMonitor::GetNotificationId(
+    const std::string& extension_id) {
+  return kNotificationIdPrefix + extension_id;
+}
+
+void ExtensionStorageMonitor::OnStorageThresholdExceeded(
+    const std::string& extension_id,
+    int64 next_threshold,
+    int64 current_usage) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  const Extension* extension = ExtensionRegistry::Get(context_)->
+      GetExtensionById(extension_id, ExtensionRegistry::EVERYTHING);
+  if (!extension)
+    return;
+
+  ExtensionPrefs* prefs = ExtensionPrefs::Get(context_);
+  DCHECK(prefs);
+  prefs->SetNextStorageThreshold(extension->id(), next_threshold);
+
+  const int kIconSize = extension_misc::EXTENSION_ICON_LARGE;
+  ExtensionResource resource =  IconsInfo::GetIconResource(
+      extension, kIconSize, ExtensionIconSet::MATCH_BIGGER);
+  ImageLoader::Get(context_)->LoadImageAsync(
+      extension, resource, gfx::Size(kIconSize, kIconSize),
+      base::Bind(&ExtensionStorageMonitor::OnImageLoaded,
+                 weak_ptr_factory_.GetWeakPtr(),
+                 extension_id,
+                 current_usage));
+}
+
+void ExtensionStorageMonitor::OnImageLoaded(
+    const std::string& extension_id,
+    int64 current_usage,
+    const gfx::Image& image) {
+  const Extension* extension = ExtensionRegistry::Get(context_)->
+      GetExtensionById(extension_id, ExtensionRegistry::EVERYTHING);
+  if (!extension)
+    return;
+
+  // Remove any existing notifications to force a new notification to pop up.
+  std::string notification_id(GetNotificationId(extension_id));
+  message_center::MessageCenter::Get()->RemoveNotification(
+      notification_id, false);
+
+  message_center::RichNotificationData notification_data;
+  notification_data.buttons.push_back(message_center::ButtonInfo(
+      l10n_util::GetStringUTF16(extension->is_app() ?
+          IDS_EXTENSION_STORAGE_MONITOR_BUTTON_DISMISS_APP :
+          IDS_EXTENSION_STORAGE_MONITOR_BUTTON_DISMISS_EXTENSION)));
+
+  scoped_ptr<message_center::Notification> notification;
+  notification.reset(new message_center::Notification(
+      message_center::NOTIFICATION_TYPE_SIMPLE,
+      notification_id,
+      l10n_util::GetStringUTF16(IDS_EXTENSION_STORAGE_MONITOR_TITLE),
+      l10n_util::GetStringFUTF16(
+          IDS_EXTENSION_STORAGE_MONITOR_TEXT,
+          base::UTF8ToUTF16(extension->name()),
+          base::IntToString16(current_usage / kMBytes)),
+      image,
+      base::string16() /* display source */,
+      message_center::NotifierId(
+          message_center::NotifierId::SYSTEM_COMPONENT, kSystemNotifierId),
+      notification_data,
+      new message_center::HandleNotificationButtonClickDelegate(base::Bind(
+          &ExtensionStorageMonitor::OnNotificationButtonClick,
+          weak_ptr_factory_.GetWeakPtr(),
+          extension_id))));
+  notification->SetSystemPriority();
+  message_center::MessageCenter::Get()->AddNotification(notification.Pass());
+}
+
+void ExtensionStorageMonitor::OnNotificationButtonClick(
+    const std::string& extension_id, int button_index) {
+  switch (button_index) {
+    case BUTTON_DISABLE_NOTIFICATION: {
+      DisableStorageMonitoring(extension_id);
+      break;
+    }
+    default:
+      NOTREACHED();
+  };
+}
+
+void ExtensionStorageMonitor::DisableStorageMonitoring(
+    const std::string& extension_id) {
+  StopMonitoringStorage(extension_id);
+
+  ExtensionPrefs* prefs = ExtensionPrefs::Get(context_);
+  DCHECK(prefs);
+  prefs->SetStorageNotificationsEnabled(extension_id, false);
+
+  message_center::MessageCenter::Get()->RemoveNotification(
+      GetNotificationId(extension_id), false);
+}
+
+void ExtensionStorageMonitor::StartMonitoringStorage(
+    const Extension* extension) {
+  if (!extension->HasAPIPermission(APIPermission::kUnlimitedStorage))
+    return;
+
+  // Do not monitor storage for component extensions.
+  if (extension->location() == Manifest::COMPONENT)
+    return;
+
+  // First apply this feature only to experimental ephemeral apps. If it works
+  // well, roll it out to all extensions and apps.
+  if (!extension->is_ephemeral() && !enable_for_all_extensions_)
+    return;
+
+  ExtensionPrefs* prefs = ExtensionPrefs::Get(context_);
+  DCHECK(prefs);
+  if (!prefs->StorageNotificationsEnabled(extension->id()))
+    return;
+
+  // Lazily create the storage monitor proxy on the IO thread.
+  if (!storage_observer_.get()) {
+    storage_observer_ =
+        new StorageEventObserver(weak_ptr_factory_.GetWeakPtr());
+  }
+
+  GURL site_url =
+      extensions::util::GetSiteForExtensionId(extension->id(), context_);
+  content::StoragePartition* storage_partition =
+      content::BrowserContext::GetStoragePartitionForSite(context_, site_url);
+  DCHECK(storage_partition);
+  scoped_refptr<quota::QuotaManager> quota_manager(
+      storage_partition->GetQuotaManager());
+
+  GURL storage_origin(site_url.GetOrigin());
+  if (extension->is_hosted_app())
+    storage_origin = AppLaunchInfo::GetLaunchWebURL(extension).GetOrigin();
+
+  int next_threshold = prefs->GetNextStorageThreshold(extension->id());
+  if (next_threshold == 0) {
+    // The next threshold is written to the prefs after the initial threshold is
+    // exceeded.
+    next_threshold = extension->is_ephemeral() ? initial_ephemeral_threshold_
+                                               : initial_extension_threshold_;
+  }
+
+  BrowserThread::PostTask(
+      BrowserThread::IO,
+      FROM_HERE,
+      base::Bind(&StorageEventObserver::StartObservingForExtension,
+                 storage_observer_,
+                 quota_manager,
+                 extension->id(),
+                 storage_origin,
+                 next_threshold,
+                 observer_rate_));
+}
+
+void ExtensionStorageMonitor::StopMonitoringStorage(
+    const std::string& extension_id) {
+  if (!storage_observer_.get())
+    return;
+
+  BrowserThread::PostTask(
+      BrowserThread::IO,
+      FROM_HERE,
+      base::Bind(&StorageEventObserver::StopObservingForExtension,
+                 storage_observer_,
+                 extension_id));
+}
+
+void ExtensionStorageMonitor::StopMonitoringAll() {
+  ExtensionRegistry* registry = ExtensionRegistry::Get(context_);
+  DCHECK(registry);
+  registry->RemoveObserver(this);
+
+  if (!storage_observer_.get())
+    return;
+
+  BrowserThread::PostTask(
+      BrowserThread::IO,
+      FROM_HERE,
+      base::Bind(&StorageEventObserver::StopObserving, storage_observer_));
+
+  storage_observer_ = NULL;
+}
+
+}  // namespace extensions