Add CdmWrapper to support multiple CDM versions in CdmAdapter.

media/cdm/ppapi/linked_ptr.h

Index: media/cdm/ppapi/linked_ptr.h
diff --git a/media/cdm/ppapi/linked_ptr.h b/media/cdm/ppapi/linked_ptr.h
index f3eccbbcf0e5d8e614b12ecf3f7a99e374f15e31..1e47a03771dfc13ceafbf96e9c64d5dd990d2682 100644
--- a/media/cdm/ppapi/linked_ptr.h
+++ b/media/cdm/ppapi/linked_ptr.h
@@ -115,6 +115,7 @@ class linked_ptr {
     capture(ptr);
   }
   T* get() const { return value_; }
+  operator T*() const { return value_; }

[ddorwin, 2013/10/18 22:17:01]

You probably don't need this based on my comments. Also, I think it's better to
avoid modifying this in ways that base/ does not have, especially if the impact
is just a few more characters in a small number of places.

[xhwang, 2013/10/18 23:03:52]

It's used in a lot of places in CdmAdapter. So I'd like to keep this change.
WDYT?

[ddorwin, 2013/10/18 23:45:56]

As discussed, this is fine.

   T* operator->() const { return value_; }
   T& operator*() const { return *value_; }
   // Release ownership of the pointed object and returns it.