Move NPAPI implementation out of webkit/plugins/npapi and into content.

Move NPAPI implementation out of webkit/plugins/npapi and into content.

Notes:
-gtk_plugin_container_manager* and gtk_plugin_container* move to content/browser/renderer_host/ since that's all where they're used
-plugin_list* and plugin_constants_win* move to content/common as they're used by child processes and the browser
-webplugin_impl* and webplugin_page_delegate.h move to content/renderer as that's where they're used. I will remove webplugin_page_delegate.h in a followup change as it's no longer needed.
-the rest moves to content/child/npapi
-a few constants moved from plugin_constants_win.h to plugin_util.h temporarily

BUG=237249
TBR=scottmg

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=212485

[jam, 2013-07-18 23:04:45]

Apologies for the size of this change. I had tried to find a way to move files a
few at a time, but there are so many interdependencies that it wasn't possible.

[scottmg, 2013-07-19 02:16:01]

lgtm

[scottmg, 2013-07-19 02:23:46]

https://codereview.chromium.org/19761007/diff/39001/content/child/npapi/plugi...
File content/child/npapi/plugin_stream_url.h (right):

https://codereview.chromium.org/19761007/diff/39001/content/child/npapi/plugi...
content/child/npapi/plugin_stream_url.h:5: #ifndef
WEBKIT_PLUGINS_NPAPI_PLUGIN_STREAM_URL_H_
missed updating header guard here