such history exists in a BigQuery table, but it is currently not published. dpranke@, packrat@ and I discussed this earlier, but there was no decision to publish this data. I will ping an internal thread about it.

Note that test results are stored in a different table (that I don't own), so I cannot say much about that.

Thank you for clarification. Hope builds and tests statistic will be accessible externally.

Could you (or somebody else) please also advise about "Tryjobs" section in each commit (in https://chromium-review.googlesource.com/c/chromium/src/+/1040925 for example)?
As I understand this section contains builds results for any specific commit.
The question is who and how defines which platforms should be built for each commit? Is there any system in this process?
And why full set of layout, unit, etc. tests is not run for each commit before merging?

a mailing list is more appropriate for these questions than this bug. I've replied there https://groups.google.com/a/chromium.org/forum/#!topic/infra-dev/S5iKmHQHlL0

We're not likely to provide "each build that was ever run"; storage costs money and the value of the build declines over time. I expect we wouldn't want to keep most builds for more than 6-12 months. 

As nodir@ says, the answers to the other questions are best answered elsewhere.

let's continue in https://groups.google.com/a/chromium.org/forum/#!topic/infra-dev/S5iKmHQHlL0