Unlock mouse when <webview> loses focus
Normally when a view loses focus RenderWidgetHostImpl::Blur() is called, which unlocks the mouse. In gtk https://code.google.com/p/chromium/codesearch#chromium/src/content/browser/renderer_host/render_widget_host_view_gtk.cc&rcl=
1366953149&l=257 unlocks the mouse. However, since the guest view doesn't have this equivalent, it doesn't call Blur() or unlock the mouse.
BUG=235934
Review URL: https://chromiumcodereview.appspot.com/
14314007
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@197369 0039d316-1c4b-4281-b951-d872f2087c98