Security update of chromium (important)

Google chromium was updated to 56.0.2924.87:

• Various small fixes
• Disabled option to enable/disable plugins in the chrome://plugins

• Changed the build requirement of libavformat to library version
  57.41.100, as included in ffmpeg 3.1.1, as only this version properly
  supports the public AVStream API ‘codecpar’.

It also contains the version update to 56.0.2924.76 (bsc#1022049):
- CVE-2017-5007: Universal XSS in Blink
- CVE-2017-5006: Universal XSS in Blink
- CVE-2017-5008: Universal XSS in Blink
- CVE-2017-5010: Universal XSS in Blink
- CVE-2017-5011: Unauthorised file access in Devtools
- CVE-2017-5009: Out of bounds memory access in WebRTC
- CVE-2017-5012: Heap overflow in V8
- CVE-2017-5013: Address spoofing in Omnibox
- CVE-2017-5014: Heap overflow in Skia
- CVE-2017-5015: Address spoofing in Omnibox
- CVE-2017-5019: Use after free in Renderer
- CVE-2017-5016: UI spoofing in Blink
- CVE-2017-5017: Uninitialised memory access in webm video
- CVE-2017-5018: Universal XSS in chrome://apps
- CVE-2017-5020: Universal XSS in chrome://downloads
- CVE-2017-5021: Use after free in Extensions
- CVE-2017-5022: Bypass of Content Security Policy in Blink
- CVE-2017-5023: Type confusion in metrics
- CVE-2017-5024: Heap overflow in FFmpeg
- CVE-2017-5025: Heap overflow in FFmpeg
- CVE-2017-5026: UI spoofing. Credit to Ronni Skansing

• Enable VAAPI hardware accelerated video decoding.

• Chromium 55.0.2883.87:

  • various fixes for crashes and specific wesites
  • update Google pinned certificates