Make NTPTile copyable.

components/ntp_tiles/ntp_tile.h

Index: components/ntp_tiles/ntp_tile.h
diff --git a/components/ntp_tiles/ntp_tile.h b/components/ntp_tiles/ntp_tile.h
index e82cd4db3e509c1182f95d2c8fcd687d0ddfc474..88b34bd0162c68b1113ed3f8863dd8b4ad8d0fc8 100644
--- a/components/ntp_tiles/ntp_tile.h
+++ b/components/ntp_tiles/ntp_tile.h
@@ -43,6 +43,8 @@ struct NTPTile {
   NTPTile(NTPTile&&);
   NTPTile& operator=(NTPTile&&);
 
+  NTPTile Copy() const;

[Marc Treib, 2016/09/15 09:10:27]

Hm, at this point, we might as well just remove the DISALLOW_COPY_AND_ASSIGN and
let the thing be copyable the regular way. (Then we probably could also remove
the move ctor and move assignment implementations.)
WDYT?

[sfiera, 2016/09/21 08:56:28]

Sure, done. (I think I was channeling google3's extreme implicit-copy avoidance)

[Marc Treib, 2016/09/21 08:58:06]

We mostly have that in Chromium as well, but in this case it's IMO fine to have
it copyable. You might want to put a "Copy and assign allowed" comment in place
of the DISALLOW_COPY_AND_ASSIGN.

[sfiera, 2016/09/21 09:12:58]

I had to add the default copy constructor explicitly for a compiler check, so I
figure I'll let that stand as the indication that copy is allowed.

+
  private:
   DISALLOW_COPY_AND_ASSIGN(NTPTile);
 };