Do not use HW H.264 encoder on Nexus 7.

Do not use HW H.264 encoder on Nexus 7.

H.264 HW encoder on some Nexus 7 models have
poor bitrate control.

R=jiayl@webrtc.org

Committed: https://chromium.googlesource.com/external/webrtc/+/194cceadae19a105074d4998408f06186ed43e42

[AlexG, 2015-08-31 22:46:48]

glaznev@webrtc.org changed reviewers:
+ jiayl@webrtc.org

[AlexG, 2015-08-31 22:46:48]

PTAL

[jiayl2, 2015-09-01 16:47:56]

lgtm

There may be more devices having the problem. Can we detect this in code and
save the preference in the app to avoid it in future calls?

[AlexG, 2015-09-01 17:36:08]

On 2015/09/01 16:47:56, jiayl2 wrote:
> lgtm
> 
> There may be more devices having the problem. Can we detect this in code and
> save the preference in the app to avoid it in future calls?

Yes, I was thinking of adding bitrate tracker to HW encoder to track
actual/target bitrate ratio and adjust target bitrate for devices with poor
bitrate control. This can also can be used to ban codec from being used if ratio
is too big.

The problem may be specific to certain QCOM chip revision - some QCOM devices
have good quality H.264 encoder, but some have this problem. May need further
investigation.

[AlexG, 2015-09-01 17:36:53]

Committed patchset #1 (id:1) manually as
194cceadae19a105074d4998408f06186ed43e42 (presubmit successful).