Reason for revert: Fixing perf tests. Original issue's description: > Revert of Delete VideoFrame default constructor, and IsZeroSize method. (patchset #5 id:80001 of https://codereview.webrtc.org/2541863002/ ) > > Reason for revert: > Crashes perf tests, e.g., > > ./out/Debug/webrtc_perf_tests --gtest_filter='FullStackTest.ScreenshareSlidesVP8_2TL_VeryLossyNet' > > dies with an assert related to rtc::Optional. > > Original issue's description: > > Delete VideoFrame default constructor, and IsZeroSize method. > > > > This ensures that the video_frame_buffer method never can return a > > null pointer. > > > > BUG=webrtc:6591 > > > > Committed: https://crrev.com/bfcf561923a42005e4c7d66d8e72e5932155f997 > > Cr-Commit-Position: refs/heads/master@{#15574} > > TBR=magjed@webrtc.org,stefan@webrtc.org > # Skipping CQ checks because original CL landed less than 1 days ago. > NOPRESUBMIT=true > NOTREECHECKS=true > NOTRY=true > BUG=webrtc:6591 > > Committed: https://crrev.com/0989fbcad2ca4eb5805a77e8ebfefd3af06ade23 > Cr-Commit-Position: refs/heads/master@{#15597} TBR=magjed@webrtc.org,stefan@webrtc.org # Skipping CQ checks because original CL landed less than 1 days ago. NOPRESUBMIT=true NOTREECHECKS=true NOTRY=true BUG=webrtc:6591 Review-Url: https://codereview.webrtc.org/2574183002 Cr-Commit-Position: refs/heads/master@{#15633}