Suppress redundant seeks to within same usec

Suppress redundant seeks to within same usec

Don't commit this until this is confirmed, and probably until we add some kind of testing to reveal issue + verify fix.

This is a candidate fix CL, but need to first confirm that it is possible for such redundant seeks to occur with Blink + WMPI.

[wolenetz, 2013-10-01 19:51:48]

PS1 is broken:

https://codereview.chromium.org/24267018/diff/1/content/renderer/media/webmed...
File content/renderer/media/webmediaplayer_impl.cc (right):

https://codereview.chromium.org/24267018/diff/1/content/renderer/media/webmed...
content/renderer/media/webmediaplayer_impl.cc:345: if (seeking_ && new_seek_time
== seek_time_) {
This is incorrect; I'll need to fix this in subsequent PS.
seek(1)+seek(2)+seek(1) collapses to just seek(1) with a CancelPendingSeek(2)
that causes kAborted demuxer buffer reads until someone later issues seek(2)
that issues StartWaitingForSeek(2) or until someone later issues a non-redundant
set of seeks such that there eventually is a matching
CancelPendingSeek+StartWaitingForSeek call.

See where similar broken optimization was fixed for Chrome for Android in
https://src.chromium.org/viewvc/chrome?view=rev&revision=226166

[wolenetz, 2015-06-09 19:59:02]

On 2013/10/01 19:51:48, wolenetz wrote:
> PS1 is broken:
> 
>
https://codereview.chromium.org/24267018/diff/1/content/renderer/media/webmed...
> File content/renderer/media/webmediaplayer_impl.cc (right):
> 
>
https://codereview.chromium.org/24267018/diff/1/content/renderer/media/webmed...
> content/renderer/media/webmediaplayer_impl.cc:345: if (seeking_ &&
new_seek_time
> == seek_time_) {
> This is incorrect; I'll need to fix this in subsequent PS.
> seek(1)+seek(2)+seek(1) collapses to just seek(1) with a CancelPendingSeek(2)
> that causes kAborted demuxer buffer reads until someone later issues seek(2)
> that issues StartWaitingForSeek(2) or until someone later issues a
non-redundant
> set of seeks such that there eventually is a matching
> CancelPendingSeek+StartWaitingForSeek call.
> 
> See where similar broken optimization was fixed for Chrome for Android in
> https://src.chromium.org/viewvc/chrome?view=rev&revision=226166

Closing this old CL, since there is a current one
(https://codereview.chromium.org/1164343003/) containing a fixed version of this
along with a fix for WMPI::currentTime() racing a previous pipeline::seek() and
returning incorrect time.