media: Add static MojoCdmService::GetCdm().

media/mojo/services/mojo_cdm_service.h

Index: media/mojo/services/mojo_cdm_service.h
diff --git a/media/mojo/services/mojo_cdm_service.h b/media/mojo/services/mojo_cdm_service.h
index c669a74b73b9fd3d4f14da7f374ae8b5164c7e6b..2e5f077daa89081cf4dd6c13bdc65574db33e5b9 100644
--- a/media/mojo/services/mojo_cdm_service.h
+++ b/media/mojo/services/mojo_cdm_service.h
@@ -25,6 +25,16 @@ class CdmFactory;
 // media::MediaKeys.
 class MojoCdmService : public interfaces::ContentDecryptionModule {
  public:
+  // Get the CDM associated with |cdm_id|, which is unique per process.
+  // Can be called on any thread. The returned CDM may be used on a different
+  // thread only when it is safe to do so.

[Tima Vaisburd, 2015/11/18 01:24:20]

"only when it is safe to do so" - unclear, do you mean that the thread safety of
this MojoCdmService does not imply the thread safety of MediaKeys?

[xhwang, 2015/11/18 18:45:39]

Done.

+  // Note: This provides a generic hack to get the CDM in the process where
+  // MojoMeidaApplication is running, regardless of which render process or

[Tima Vaisburd, 2015/11/18 01:24:20]

s/Meida/Media/

[xhwang, 2015/11/18 18:45:39]

Done.

+  // render frame the caller is associated with. In the future, we should move
+  // all out-of-process media players into the MojoMediaApplicaiton so that we
+  // can use MojoCdmServiceContext (per render frame) to get the CDM.
+  static scoped_refptr<MediaKeys> GetCdm(int cdm_id);
+
   // Constructs a MojoCdmService and strongly binds it to the |request|.
   MojoCdmService(
       base::WeakPtr<MojoCdmServiceContext> context,