Provide monitoring of usage for a storage type and origin

webkit/browser/quota/storage_observer.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 WEBKIT_BROWSER_QUOTA_STORAGE_OBSERVER_H_
+#define WEBKIT_BROWSER_QUOTA_STORAGE_OBSERVER_H_
+
+#include "base/basictypes.h"
+#include "base/time/time.h"
+#include "url/gurl.h"
+#include "webkit/browser/quota/quota_client.h"
+#include "webkit/common/quota/quota_types.h"
+
+namespace quota {
+
+// This interface is implemented by observers that wish to monitor storage
+// events, such as changes in quota or usage.
+class WEBKIT_STORAGE_BROWSER_EXPORT StorageObserver {
+ public:
+  struct WEBKIT_STORAGE_BROWSER_EXPORT Filter {
+    // The storage type to monitor. This must not be kStorageTypeUnknown or
+    // kStorageTypeQuotaNotManaged.
+    StorageType storage_type;
+
+    // The origin to monitor usage for. Must be specified.
+    GURL origin;
+
+    Filter();
+    Filter(StorageType storage_type, const GURL& origin);
+    bool operator==(const Filter& other) const;
+  };
+
+  struct WEBKIT_STORAGE_BROWSER_EXPORT MonitorParams {
+    // Storage type and origin to monitor.
+    Filter filter;
+
+    // The rate at which storage events will be fired. Events will be fired at
+    // approximately this rate, or when a storage status change has been
+    // detected, whichever is the least frequent.
+    base::TimeDelta rate;
+
+    // If set to true, the observer will be dispatched an event when added.
+    bool dispatch_initial_state;
+
+    MonitorParams();
+    MonitorParams(StorageType storage_type,
+                  const GURL& origin,
+                  const base::TimeDelta& rate,
+                  bool get_initial_state);
+    MonitorParams(const Filter& filter,
+                  const base::TimeDelta& rate,
+                  bool get_initial_state);
+  };
+
+  struct WEBKIT_STORAGE_BROWSER_EXPORT Event {
+    // The storage type and origin monitored.
+    Filter filter;
+
+    // The current usage corresponding to the filter.
+    int64 usage;
+
+    // The quota corresponding to the filter.
+    int64 quota;
+
+    Event();
+    Event(const Filter& filter, int64 usage, int64 quota);
+    bool operator==(const Event& other) const;
+  };
+
+  // Will be called on the IO thread when a storage event occurs.
+  virtual void OnStorageEvent(const Event& event) = 0;
+
+ protected:
+  virtual ~StorageObserver() {}
+};
+
+}  // namespace quota
+
+#endif  // WEBKIT_BROWSER_QUOTA_STORAGE_OBSERVER_H_