Implement QuotaTemporaryStorageEvictor.

webkit/quota/quota_temporary_storage_evictor.h

Index: webkit/quota/quota_temporary_storage_evictor.h
diff --git a/webkit/quota/quota_temporary_storage_evictor.h b/webkit/quota/quota_temporary_storage_evictor.h
new file mode 100644
index 0000000000000000000000000000000000000000..81a4314de3d818b286093b427c2cfaf415d7d978
--- /dev/null
+++ b/webkit/quota/quota_temporary_storage_evictor.h
@@ -0,0 +1,66 @@
+// Copyright (c) 2011 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_QUOTA_QUOTA_TEMPORARY_STORAGE_EVICTOR_H_
+#define WEBKIT_QUOTA_QUOTA_TEMPORARY_STORAGE_EVICTOR_H_
+#pragma once
+
+#include "base/message_loop_proxy.h"
+#include "base/memory/scoped_callback_factory.h"
+#include "base/timer.h"
+#include "webkit/quota/quota_manager.h"
+#include "webkit/quota/quota_types.h"
+
+class GURL;
+
+namespace quota {
+
+class QuotaTemporaryStorageEvictor {
+ public:
+  QuotaTemporaryStorageEvictor(
+      QuotaEvictionHandler* quota_eviction_handler,
+      int64 interval_ms,
+      scoped_refptr<base::MessageLoopProxy> io_thread);
+  virtual ~QuotaTemporaryStorageEvictor();
+
+  void Start();
+
+  bool repeated_eviction() const { return repeated_eviction_; }
+  void set_repeated_eviction(bool repeated_eviction) {
+    repeated_eviction_ = repeated_eviction;
+  }
+
+  static const double kUsageRatioToStartEviction;
+  const int64 kAvailableDiskSpaceToStartEviction;

[kinuko, 2011/05/20 06:41:14]

This is not static since you imagine we may give different value per instance? 
If so I think we usually use our usual lower_with_underscore_ naming even for
constant vars.  Otherwise this could be simply a static const var?

[Dai Mikurube (NOT FULLTIME), 2011/05/20 07:36:54]

Hmm, I guess I did two mistakes :
1. I read your previous comments just to rename it.  But it looks like you
didn't say so.
2. I (wrongly) found all constant variables should start with 'k' at
http://google-styleguide.googlecode.com/svn/trunk/cppguide.xml#Constant_Names . 
But it looks like saying "All *compile-time* constants..." by reading precisely.

Are they correct?

I guess we've discussed to make this variable (which contains the threshold of
available disk space to start eviction) changeable by a kind of environment.

[kinuko, 2011/05/20 08:27:02]

Yeah the detailed rule is hidden in the expandable section.
I think so.
Ok let me try to make the points clearer:
* I think we'd better use compile-time constant for the magic number (1000 *
1000 * 500). (This is what I wanted to say in the 1st comment)
* Giving the fact that we may want to change the
min-available-disk-space-to-start-eviction, how about:
- call the compile-time constant 'default' something, like
kDefaultMinAvailableDiskSpaceToStartEviction
- change the member variable available_disk_space_to_start_eviction_ (please
append trailing '_') back to non-const
- initialize the member variable with the constant in the constructor.

Does that make sense?

[Dai Mikurube (NOT FULLTIME), 2011/05/20 09:33:07]

Ah, make sense.  It was just a temporary value to run it as trial (not ready for
review/commit) I had to have a discussion about "what is the initial value for
that?"

I agree with your suggestion.  I'll fix this.

# I might be happy if you could avoid using pronouns...

[kinuko, 2011/05/20 09:40:33]

Will try!

+
+ private:
+  friend struct QuotaTemporaryStorageEvictorDeleter;
+  friend class QuotaTemporaryStorageEvictorTest;
+
+  void MayStartEviction(int interval_ms);
+  void GetUsageAndQuotaThenEvict();
+  void EvictIfRequired(
+      QuotaStatusCode status,
+      int64 usage,
+      int64 quota,
+      int64 physical_available_space);
+  void DoEvict(const GURL& origin);
+  void OnEvictionCompleted(QuotaStatusCode status);
+
+  QuotaEvictionHandler* quota_eviction_handler_;

[kinuko, 2011/05/20 06:41:14]

Can we add a comment like "Not owned; eviction_handler owns us." ?

[Dai Mikurube (NOT FULLTIME), 2011/05/20 07:36:54]

Done.

+
+  int64 interval_ms_;
+  bool repeated_eviction_;
+  scoped_refptr<base::MessageLoopProxy> io_thread_;
+
+  base::OneShotTimer<QuotaTemporaryStorageEvictor> timer_;
+
+  base::ScopedCallbackFactory<QuotaTemporaryStorageEvictor> callback_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(QuotaTemporaryStorageEvictor);
+};
+
+}  // namespace quota
+
+#endif  // WEBKIT_QUOTA_QUOTA_TEMPORARY_STORAGE_EVICTOR_H_