Add ExtensionsApiClient interface, use it in the storage API SettingsFrontend

chrome/browser/extensions/chrome_extensions_browser_client.h

 // Copyright 2013 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 CHROME_BROWSER_EXTENSIONS_CHROME_EXTENSIONS_BROWSER_CLIENT_H_
 #define CHROME_BROWSER_EXTENSIONS_CHROME_EXTENSIONS_BROWSER_CLIENT_H_
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/lazy_instance.h"
 #include "base/memory/scoped_ptr.h"
 #include "chrome/browser/extensions/chrome_notification_observer.h"
 #include "extensions/browser/extensions_browser_client.h"
 
 class CommandLine;
 
 namespace content {
 class BrowserContext;
 }
 
 namespace extensions {
 
+class ChromeExtensionsApiClient;
+
 // Implementation of extensions::BrowserClient for Chrome, which includes
 // knowledge of Profiles, BrowserContexts and incognito.
 //
 // NOTE: Methods that do not require knowledge of browser concepts should be
 // implemented in ChromeExtensionsClient even if they are only used in the
 // browser process (see chrome/common/extensions/chrome_extensions_client.h).
 class ChromeExtensionsBrowserClient : public ExtensionsBrowserClient {
  public:
   ChromeExtensionsBrowserClient();
   virtual ~ChromeExtensionsBrowserClient();
@@ skipping 36 matching lines @@
   virtual ApiActivityMonitor* GetApiActivityMonitor(
       content::BrowserContext* context) OVERRIDE;
   virtual ExtensionSystemProvider* GetExtensionSystemFactory() OVERRIDE;
 
  private:
   friend struct base::DefaultLazyInstanceTraits<ChromeExtensionsBrowserClient>;
 
   // Observer for Chrome-specific notifications.
   ChromeNotificationObserver notification_observer_;
 
+  // Client for API implementations.
+  scoped_ptr<ChromeExtensionsApiClient> api_client_;

[Devlin, 2014/03/03 17:07:59]

Would it make sense to put this in ExtensionsBrowserClient (since it will
presumably be in all implementations)?

[James Cook, 2014/03/03 19:53:09]

Unless you feel strongly I'd like to keep it here. It seems like we can either
have ExtensionsBrowserClient take care of Set(instance) and Set(NULL) in its
constructor/destructor (which SGTM) or we can have a public Set(foo) method that
takes ownership of |foo|.

Maybe there's some way to accomplish both but it seems like it would be ornate
and I would prefer the former.

[Devlin, 2014/03/03 20:25:27]

I don't feel strongly at all, so this is fine.  But, for what it's worth, all I
was thinking was:
class ExtensionsBrowserClient {
ExtensionsBrowserClient(ExtensionsApiClient* client) : api_client_(client) {}
...
scoped_ptr<ExtensionsApiClient> api_client_;
};

ChromeExtensionsBrowserClient::ChromeExtensionsBrowserClient()
    : ExtensionsBrowserClient(new ChromeExtensionsApiClient) {...}

ShellExtensionsBrowserClient::ShellExtensionsBrowserClient()
    : ExtensionsBrowserClient(new ShellExtensionsApiClient) {...}

which doesn't seem overlay ornate.  But again, I'm fine with this.

[Yoyo Zhou, 2014/03/04 19:55:04]

Do we want to be able to handle ExtensionsApiClient::Get() ever returning NULL?

+
   DISALLOW_COPY_AND_ASSIGN(ChromeExtensionsBrowserClient);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_CHROME_EXTENSIONS_BROWSER_CLIENT_H_