Fix use_external_begin_frame support and update VSync setters (fixes issue #2618)

This PR removes the extra parameter from the ui::Compositor constructor, which resulted in software rendering being forced whenever use_external_begin_frame was enabled, and therefore broke OSR in Chromium 73+ builds. It also replaces the old SetAuthoritativeVsyncInterval calls with calls to SetDisplayVSyncParameters and UpdateVSyncParameters.