Extract ProcessManager from ExtensionSystem.

extensions/browser/process_manager_factory.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 EXTENSIONS_BROWSER_PROCESS_MANAGER_FACTORY_H_
+#define EXTENSIONS_BROWSER_PROCESS_MANAGER_FACTORY_H_
+
+#include "base/memory/singleton.h"
+#include "components/keyed_service/content/browser_context_keyed_service_factory.h"
+
+namespace extensions {
+
+class ProcessManager;
+

[not at google - send to devlin, 2014/10/24 20:29:47]

Typically these Factories are implementation details of the classes themselves,
and are hidden away in the .cc file, if I'm understanding this. I.e. the only
part of this class you need to expose anywhere is what gets called by
ProcessManager::Get.

[Reilly Grant (use Gerrit), 2014/10/24 20:37:23]

The coding standard suggests one class per .cc file. There are also consumers
that directly access the factory directly, such as services that depend on it
and places where the "IfExists" version of Get is called. I put this method only
on the factory since it feels like more of a factory detail than something that
belongs in ProcessManager.

[not at google - send to devlin, 2014/10/24 20:52:03]

Ah ok. Yeah I think you might need it in a separate file for declaring
dependencies anyway?

But I hardly see any normal code using the Factory versions, always accessing
through the ProcessManager::Get interface. You could add
ProcessManager::GetIfExists, but where do you need it? I've never seen it
before, so perhaps there is another way to achieve the same thing.

[Reilly Grant (use Gerrit), 2014/10/24 21:01:18]

I don't *need* to but I'd rather keep it separate. Especially since there's the
whole IncognitoProcessManager thing that may get split out of process_manager.cc
and the logic for deciding which one to build could move into the factory.
ChromeProcessManagerDelegate needs GetIfExists it to be able to avoid creating a
new ProcessManager during profile destruction. I kept it in
ProcessManagerFactory because it feels more like asking the factory "did you
create one of these already" rather than something ProcessManager would know
about. I can add the wrapper if you think it would feel more consistent that
way.

+class ProcessManagerFactory : public BrowserContextKeyedServiceFactory {
+ public:
+  static ProcessManager* GetForBrowserContext(content::BrowserContext* context);
+  // Returns NULL if there is no ProcessManager associated with this context.
+  static ProcessManager* GetForBrowserContextIfExists(
+      content::BrowserContext* context);
+  static ProcessManagerFactory* GetInstance();
+
+ private:
+  friend struct DefaultSingletonTraits<ProcessManagerFactory>;
+
+  ProcessManagerFactory();
+  virtual ~ProcessManagerFactory();
+
+  // BrowserContextKeyedServiceFactory
+  virtual KeyedService* BuildServiceInstanceFor(
+      content::BrowserContext* context) const override;
+  virtual content::BrowserContext* GetBrowserContextToUse(
+      content::BrowserContext* context) const override;
+
+  DISALLOW_COPY_AND_ASSIGN(ProcessManagerFactory);
+};
+
+}  // namespace extensions
+
+#endif  // EXTENSIONS_BROWSER_PROCESS_MANAGER_FACTORY_H_