This CL is the first in a series of CLs to refactor
VideoProcessing(Module) to follow Google C++ style guide and make the
code more readable.
This CL removed inheritance from Module, renames variables and makes
VideoProcessingImpl::PreprocessFrame return a frame pointer if there
is a frame to send, nullptr otherwise. The affected CLs also passes git
cl lint.
BUG=webrtc:5259
Review URL: https://codereview.webrtc.org/1482913003
Cr-Commit-Position: refs/heads/master@{#10907}
a8565425bc