media: Add MojoCdmServiceContext.

media/mojo/services/mojo_cdm_service_context.h

+// Copyright 2015 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 MEDIA_MOJO_SERVICES_MOJO_CDM_SERVICE_CONTEXT_H_
+#define MEDIA_MOJO_SERVICES_MOJO_CDM_SERVICE_CONTEXT_H_
+
+#include "base/containers/scoped_ptr_hash_map.h"
+#include "base/macros.h"
+#include "media/base/cdm_context.h"
+#include "media/base/media_export.h"
+#include "media/mojo/services/mojo_cdm_service.h"
+
+namespace media {
+
+// A class that creates, owns and manages all MojoCdmService instances.
+class MEDIA_EXPORT MojoCdmServiceContext : public CdmContextProvider {
+ public:
+  MojoCdmServiceContext();
+  ~MojoCdmServiceContext() override;
+
+  // Creates a MojoCdmService for |key_system| and weakly bind it to |request|.

[ddorwin, 2015/06/11 19:09:43]

nit: binds

[xhwang, 2015/06/11 20:58:01]

Done.

+  // The created MojoCdmService is owned by |this|. The request will be dropped
+  // if no MojoCdmService can be created.

[ddorwin, 2015/06/11 19:09:43]

Perhaps add:
", resulting in a connection error"

Is that a common way to report creation errors?

[xhwang, 2015/06/11 20:58:01]

Done.
Yes. Another way is to use a factory class to do this, so you know whether it's
not supported, or actually an unexpected connection error happened. This is what
I did in the previous CL but I found it more complex and not worth the benefit.

+  void CreateCdmService(
+      const mojo::String& key_system,
+      const mojo::String& security_origin,
+      int32_t cdm_id,
+      mojo::InterfaceRequest<mojo::ContentDecryptionModule> request);
+
+  // CdmContextProvider implementation.
+  // TODO(xhwang): The returned CdmContext can be destroyed at any time if the
+  // pipe is disconnected. When implementing SetCdm(), make sure we never

[ddorwin, 2015/06/11 19:09:43]

I think the first sentence is documentation, and the second is the TODO. Is that
right?
Well, you can keep the whole thing as a TODO if you copy the first sentence to
the interface defn (see my earlier comment).

[xhwang, 2015/06/11 20:58:01]

Done.
The interface is generic, where it knows nothing about a pipe. This comment only
applies for this particular implementation where we use a pipe.

+  // dereference garbage. For example, use media::PlayerTracker.
+  CdmContext* GetCdmContext(int32_t cdm_id) override;
+
+  // Called when there is a connection error with |service|.
+  void ServiceHadConnectionError(MojoCdmService* service);
+
+ private:
+  // A map between CDM ID and MojoCdmService. Owns all MojoCdmService created.
+  base::ScopedPtrHashMap<int32_t, scoped_ptr<MojoCdmService>> services_;
+
+  DISALLOW_COPY_AND_ASSIGN(MojoCdmServiceContext);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_MOJO_SERVICES_MOJO_CDM_SERVICE_CONTEXT_H_