Persist sessionStorage on disk.

content/public/browser/browser_context.h

 // Copyright (c) 2012 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 CONTENT_PUBLIC_BROWSER_BROWSER_CONTEXT_H_
 #define CONTENT_PUBLIC_BROWSER_BROWSER_CONTEXT_H_
 #pragma once
 
 #include "base/hash_tables.h"
 #include "base/supports_user_data.h"
@@ skipping 102 matching lines @@
   // Returns the speech input preferences. SpeechRecognitionPreferences is a
   // ref counted class, so callers should take a reference if needed.
   virtual SpeechRecognitionPreferences* GetSpeechRecognitionPreferences() = 0;
 
   // Returns true if the last time this context was open it was exited cleanly.
   // This doesn't belong here; http://crbug.com/90737
   virtual bool DidLastSessionExitCleanly() = 0;
 
   // Returns a special storage policy implementation, or NULL.
   virtual quota::SpecialStoragePolicy* GetSpecialStoragePolicy() = 0;
+
+  // Returns true if the sessionStorage should be backed on disk. TODO(marja):
+  // Remove this when the "session storage on disk" implementation has
+  // stabilized.
+  virtual bool ShouldSaveSessionStorageOnDisk() = 0;

[michaeln, 2012/06/05 01:41:07]

There's a bunch of indirection with 'should save' (in profile and here) just
because the cmd line switch is defined up in the chrome library. Maybe we should
define that string constant in the in the content library instead? It'd be nice
to avoid these changes to Profile and BrowserContext may to temporarily put this
behind a flag.

[marja, 2012/06/06 13:37:10]

Done. The flag is in DOMStorageContextImpl ctor.

[michaeln, 2012/06/08 01:04:20]

Drat, I think i may have given you a bum steer around this one :( The flag in
DOMStorageContextImpl ctor definitely works to start with, but...

I wasn't thinking about the possibility of other 'content' library embedders
besides chrome. On second thought, it might be nice to have a big master on/off
switch for enabling persistent session storage stuff in the content library...
for embedders with no intention of ever doing anything like 'session restore'...
could make their lives a little easier.

Having that master on/off switch on the BrowserContext could work. Another
option might be to have it on the ContentBrowserClient interface. Where ever it
goes, a name that includes 'persistent' might be helpful.

virtual bool ShouldPersistSessionStorage();

 };
 
 }  // namespace content
 
 #if defined(COMPILER_GCC)
 namespace BASE_HASH_NAMESPACE {
 
 template<>
 struct hash<content::BrowserContext*> {
   std::size_t operator()(content::BrowserContext* const& p) const {
     return reinterpret_cast<std::size_t>(p);
   }
 };
 
 }  // namespace BASE_HASH_NAMESPACE
 #endif
 
 #endif  // CONTENT_PUBLIC_BROWSER_BROWSER_CONTEXT_H_