MacViews: Consolidate BrowserWindow's fullscreen API

MacViews: Consolidate BrowserWindow's fullscreen API

"Fullscreen with Chrome" is a Mac only feature with its BrowserWindow API
guarded by #if(OSX).
I need to get BrowserView building for MacViews, so this CL refactors the API
to get rid of the ifdefs.

Started by applying Erik's patch from https://crrev.com/682873002.
Then unify the fullscreen API between Cocoa and Views:

1. Add SupportsFullscreenWithChrome() to replace the ifdefs.

2. Combine the EnterFullscreen... methods into one by adding a withChrome
   parameter to EnterFullscreen().

3. Combine AddChromeToFullscreen() and RemoveChromeToFullscreen() into
   UpdateFullscreenWithChrome().

4. Delete IsFullscreenWithoutChrome().
   It is the same as IsFullscreen() && !IsFullscreenWithChrome().

5. Rename ...WithChrome to ...WithToolbar

BUG=425229

Review URL: https://codereview.chromium.org/738933002

Cr-Commit-Position: refs/heads/master@{#305312}