<webview>: Make HandleContextMenu easier to refactor

<webview>: Make HandleContextMenu easier to refactor

In the future, BrowserPluginGuest will no longer be a WebContentsDelegate, and so special handling for guests that relies on the internal implementation details of BrowserPlugin should be moved to chrome.

BUG=364141, 330264
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=272579

[lazyboy, 2014-05-20 21:20:20]

lgtm

Also update the CL description a bit saying BrowserPluginGuest would no longer
be WCDelegate, hence we cannot do the conversion there and hence do it in
WCImpl.

[Fady Samuel, 2014-05-20 21:29:30]

I updated the comment, Nasko could you please OWNER review the
web_contents_impl.cc change? Thanks!

[nasko, 2014-05-22 20:05:35]

LGTM

I'm not an owner for WebContents though, you need someone else.

[jam, 2014-05-23 15:46:25]

lgtm

[Fady Samuel, 2014-05-23 15:48:20]

The CQ bit was checked by fsamuel@chromium.org

[commit-bot: I haz the power, 2014-05-23 15:49:24]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/fsamuel@chromium.org/296703005/1

[commit-bot: I haz the power, 2014-05-23 19:24:13]

Change committed as 272579