Added documentation to web_view.js/web_view_experimental.js regarding the webview events structure.

BUG=

Review URL: https://codereview.chromium.org/145813002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246958 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 246958
[Mac] In the collected cookies dialog, only enable the Remove button if there is a selection.

BUG=337802
TEST=Click on the page info icon, click "Show cookies", in the Allowed tab
select a site domain and the Remove button becomes enabled. Unselect and it is
disabled.

Review URL: https://codereview.chromium.org/146903002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246959 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 246959