Fix views::WebView focus for Print Preview and other web dialogs.
Focus the dialog's WebView when its WebContents is focused.
Use a FocusChangeObserver to assist with this task.
BrowserView does this for its WebViews by overriding:
WebContentsDelegate::WebContentsFocused
TODO: Cleanup the WebView/WebContents/etc. focus pattern...
(See Ben's WebView::OnWebContentsFocused TODO)
BUG=368691
TEST=Focusing between the omnibox and print preview dialogs works correctly (the omnibox loses focus, closes any dropdowns, doesn't show cursor/selection).
R=ben@chromium.org
Review URL: https://codereview.chromium.org/
431573003
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@287082 0039d316-1c4b-4281-b951-d872f2087c98