Change frame bookkeeping in VideoProcessorIntegrationTest.

Now we always process |rate_profile.num_frames| number of frames.
This means that the output of the tests in
videoprocessor_integrationtest.cc will be slightly different,
as we will no process 300 frames, instead of 299. No rate control
or quality thresholds need to be updated, however.

BUG=webrtc:6634

Review-Url: https://codereview.webrtc.org/3004583002
Cr-Original-Commit-Position: refs/heads/master@{#19515}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: ee95f874885a8489bebc54bae9c3bec26884f858
3 files changed