Add CefDisplayHandler.onFullscreenModeChange callback

[magreenblatt]

Original report by Igor_Zh (Bitbucket: Igor_Zh).

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No listener full-screen mode.
When you select a video in full screen mode, the video takes the size of the component awt but not the entire screen
This question JCEF forum I got here is a response from Mr.magreenblatt

Using:
JCEF Version = 3.2704.139
CEF Version = 3.2704.1427
Chromium Version = 51.0.2704.84
OC Windows 10

[magreenblatt]

• changed title from "Missing video preview mode in full screen" to "Add CefDisplayHandler.onFullscreenModeChange callback"
• changed priority from "major" to "minor"
• edited description