Oilpan: Make PersistentNode hold a raw pointer
Oilpan: Make PersistentNode hold a raw pointer

This CL changes:

  class PersistentNode { };
  class PersistentBase : public PersistentNode { };
  class Persistent {
    T* m_raw;
  };
  class CrossThreadPersistent {
    T* m_raw;
  };

to:

  class PersistentNode {
    void* m_raw;
  };
  class PersistentBase : public PersistentNode { };
  class Persistent { };
  class CrossThreadPersistent { };

This is a preparation for tracing the m_raw from PersistentNode and thus
remove PersistentNode::m_trace in a follow-up CL.

BUG=483380

Review URL: https://codereview.chromium.org/1159003006

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@196501 bbb929c8-8fbe-4397-9dbb-9b2b20218538

Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk