components: Cleanup class/struct fwd declarations

components/nacl/loader/nacl_ipc_adapter.h

Index: components/nacl/loader/nacl_ipc_adapter.h
diff --git a/components/nacl/loader/nacl_ipc_adapter.h b/components/nacl/loader/nacl_ipc_adapter.h
index 4ea8e0ff399e39f703afb69fb1e00702065b3ed7..1f4e6e0833bc24ff311e30793c7a889661c9f07b 100644
--- a/components/nacl/loader/nacl_ipc_adapter.h
+++ b/components/nacl/loader/nacl_ipc_adapter.h
@@ -29,7 +29,6 @@
 
 struct NaClDesc;
 struct NaClImcTypedMsgHdr;
-struct PP_Size;
 
 namespace base {
 class SingleThreadTaskRunner;
@@ -40,10 +39,6 @@ class Channel;
 struct ChannelHandle;
 }
 
-namespace ppapi {
-class HostResource;
-}
-
 // Adapts a Chrome IPC channel to an IPC channel that we expose to Native
 // Client. This provides a mapping in both directions, so when IPC messages
 // come in from another process, we rewrite them and allow them to be received