WebRTC: One WebRTC Video can have both SW and HW VideoFrame.
WebRTC: One WebRTC Video can have both SW and HW VideoFrame.

SkCanvasVideoRenderer assumes that the VideoFrames belonging to one WebRTC
video are always either software VideoFrame or hardware VideoFrame.
However, it's not true. VideoFrame can be changed each frame.

TEST=content_browsertests WebRtcBrowserTest.CallAndVerify* on Nexus5
BUG=448014

Review URL: https://codereview.chromium.org/848683003

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#311468}

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