Change how the quota system computes the total poolsize for temporary storage

storage/browser/quota/quota_settings.h

+// Copyright 2016 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 STORAGE_BROWSER_QUOTA_QUOTA_SETTINGS_H_
+#define STORAGE_BROWSER_QUOTA_QUOTA_SETTINGS_H_
+
+#include <stdint.h>
+
+#include "base/callback.h"
+#include "base/files/file_path.h"
+#include "base/optional.h"
+#include "base/time/time.h"
+#include "storage/browser/storage_browser_export.h"
+
+namespace storage {
+
+// Settings the storage lib embedder must provide to the QuotaManager.
+struct QuotaSettings {
+  QuotaSettings() = default;
+  QuotaSettings(int64_t pool_size,
+                int64_t per_host_quota,
+                int64_t should_remain_available,
+                int64_t must_remain_available)
+      : pool_size(pool_size),
+        per_host_quota(per_host_quota),
+        should_remain_available(should_remain_available),
+        must_remain_available(must_remain_available) {}
+
+  // The target size in bytes of the shared pool of disk space the quota
+  // system allows for use by websites using HTML5 storage apis, for
+  // example an embedder may use 50% of the total volume size.
+  int64_t pool_size = 0;
+
+  // The amount in bytes of the pool an individual site may consume. The
+  // value must be less than or equal to the pool_size.
+  int64_t per_host_quota = 0;
+
+  // The amount of space that should remain available on the storage
+  // volume. As the volume approaches this limit, the quota system gets
+  // more aggressive about evicting data.
+  int64_t should_remain_available = 0;
+
+  // The amount of space that must remain available on the storage
+  // volume. As the volume approaches this limit, the quota system gets
+  // very aggressive about disallowing new data.
+  int64_t must_remain_available = 0;
+
+  // The quota system querries the embedder for the QuataSettings,
+  // but will rate limit the frequency of the querries to no more than once
+  // per refresh interval.
+  base::TimeDelta refresh_interval = base::TimeDelta::Max();
+};
+
+// Function type used to return the settings in response to a
+// GetQuotaSettingsFunc invocation. If the embedder cannot
+// produce a settings values, base::nullopt can be returned.
+using OptionalQuotaSettingsCallback =
+    base::Callback<void(base::Optional<QuotaSettings>)>;
+
+// Function type used to query the embedder about the quota manager settings.
+// This function is invoked on the UI thread.
+using GetQuotaSettingsFunc =
+    base::Callback<void(const OptionalQuotaSettingsCallback& callback)>;
+
+// Returns settings based on the size of the volume containing the storage
+// partition and a guestimate of the size required for the OS. The refresh
+// interval is 60 seconds to accomodate changes to the size of the volume.
+// Except, in the case of incognito, the poolize and quota values are based
+// on the amount of physical memory and the rerfresh interval is max'd out.
+STORAGE_EXPORT
+base::Optional<storage::QuotaSettings> CalculateNominalDynamicSettings(
+    const base::FilePath& partition_path,
+    bool is_incognito);
+
+// Returns settings with a poolsize of zero and no per host quota.
+inline QuotaSettings GetNoQuotaSettings() {
+  return QuotaSettings();
+}
+
+// Returns settings that provide given |per_host_quota| and a total poolsize of
+// five times that.
+inline QuotaSettings GetHardCodedSettings(int64_t per_host_quota) {
+  return QuotaSettings(per_host_quota * 5, per_host_quota,
+                       per_host_quota, per_host_quota);
+}
+
+}  // namespace storage
+
+#endif  // STORAGE_BROWSER_QUOTA_QUOTA_MANAGER_H_