Implement pointer lock across outer/inner WebContents.

extensions/browser/guest_view/web_view/web_view_guest.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "extensions/browser/guest_view/web_view/web_view_guest.h"
 
 #include <stddef.h>
 
 #include <utility>
 
@@ skipping 1357 matching lines @@
 
 void WebViewGuest::ExitFullscreenModeForTab(WebContents* web_contents) {
   SetFullscreenState(false);
 }
 
 bool WebViewGuest::IsFullscreenForTabOrPending(
     const WebContents* web_contents) const {
   return is_guest_fullscreen_;
 }
 
+void WebViewGuest::RequestToLockMouse(WebContents* web_contents,
+                                      bool user_gesture,
+                                      bool last_unlocked_by_target) {
+  RequestPointerLockPermission(
+      user_gesture, last_unlocked_by_target,
+      base::Bind(
+          [](WebContents* web_contents, bool allowed) {

[ncarter (slow), 2016/12/22 00:01:07]

Why not:

base::Bind(base::IgnoreResult(&WebContents::GotResponseToLockMouseRequest),
base::Unretained(web_contents)); ?

I think dcheng had mentioned that lambdas w/ Bind are to be avoided if possible,
because we prefer the forms that make the caller use base::Unretained or some
other indication of pointer ownership semantics.

[lfg, 2016/12/22 19:23:55]

Oh, that's nice, I wasn't aware of base::IgnoreResult. Done.

+            web_contents->GotResponseToLockMouseRequest(allowed);
+          },
+          web_contents));
+}
+
 void WebViewGuest::LoadURLWithParams(
     const GURL& url,
     const content::Referrer& referrer,
     ui::PageTransition transition_type,
     bool force_navigation) {
   if (!url.is_valid()) {
     LoadAbort(true /* is_top_level */, url, net::ERR_INVALID_URL);
     NavigateGuest(url::kAboutBlankURL, false /* force_navigation */);
     return;
   }
@@ skipping 128 matching lines @@
     std::unique_ptr<base::DictionaryValue> args(new base::DictionaryValue());
     DispatchEventToView(base::MakeUnique<GuestViewEvent>(
         webview::kEventExitFullscreen, std::move(args)));
   }
   // Since we changed fullscreen state, sending a Resize message ensures that
   // renderer/ sees the change.
   web_contents()->GetRenderViewHost()->GetWidget()->WasResized();
 }
 
 }  // namespace extensions