zijiehe 05bba2be48 Several minor changes to ScreenCapturerWinMagnifier
1. Remove legacy screen-saver-blocking logic
2. tls_index_ is not a good choice, we can use thread-static
3. ScreenCapturerHelper is not designed for this scenario
4. Disable this capturer on 2+ monitors system

BUG=638802

Review-Url: https://codereview.webrtc.org/2319383002
Cr-Commit-Position: refs/heads/master@{#14342}
2016-09-22 00:25:48 +00:00
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