CL for my initial improvements (WIP): https://crrev.com/c/788643.

Thanks for looking at this!

First, one bit of functionality that I think we should try to preserve is the ability to dump all the histogram data to a file for a bug report. Right now, that can be done by simply selecting all and copying the data to save to a file. In the new UI where you plan not to show things as text, I would suggest adding a simple "Save data..." button that downloads the output as a file.

The other thing I'd like to mention is my comment on https://bugs.chromium.org/p/chromium/issues/detail?id=786689#c1

Basically, because this is an internal page that only a handful of developers will be using (vs. a billion Chrome users), I would be concerned of increasing the binary size of this supporting code too much. So while I support the improvements, let's try to make them in a way that keeps size down. (For example, it's not obvious to me that having a full-fledged polymer page is worth the binary size cost - vs. just adding some of the proposed functionality as simple html).

#2 Yep, I'm very conscious of binary size. I think adding a few usability improvements will slightly increase the binary, but be worth it for debugging. I agree it's probably not worth going to a full polymer page (I'm not sure --- does it actually cost anything if polymer is already included for other pages?)

It doesn't need to be pretty, but I think a few usability improvements as mentioned above would make life easier for people implementing or debugging metrics.

mathp@ and fdoray@ were thinking of some similar usability enhancements for their Chrome Mon innovation week project this week. cc'ing them

mgiuca@, I assume you're not actively working on this, right? So they could start with your WIP CL maybe?

Actually it's Sebastien and I

Hi,

My apologies for not finishing this off. I might just land my CL since it's pretty much working. I just did a pass over it to fix up the escaping. It depends if the reviewers (I've added asvitkine and jam) are happy to keep appending HTML to the top (and adding a <script> section), or whether they'll want it factored out. I likely don't have the time to do a bigger refactoring.

It's out for review now (https://chromium-review.googlesource.com/c/chromium/src/+/788643).

In the mean time, mathp and sebsg, maybe you can do additional work on a branch based on my above CL?

Hey Matt, we've worked on this Monday and are going in quite a drastic direction: https://chromium-review.googlesource.com/c/chromium/src/+/890627 (not actually displaying graphs yet but you can see the spirit!). 

I'm not sure that we'll be able to share code but we'll keep your functionality ideas!

Ah OK, looks like you're gutting all the code. Looks good.

Do you think this will be rolling out soon? If not, I might still try to land my code anyway (and you can just rebase it away). But if you're planning to land this week then I'll just abandon mine.

Let us see if we get somewhere with the new code. I think it's looking like we will but I can confirm in a few days.

fdegros@ sent me yet a different CL to improve this page:

https://chromium-review.googlesource.com/c/chromium/src/+/897385

Given there's three competing changes to improve this, I'd like to better understand the next steps. First, mathp@ - what's the state of your changes? Do they overlap with either of the two CLs and are you still planning to continue pursuing them?

This is the current state: https://docs.google.com/presentation/d/1M2U3bIXMd4aPd0YJZ-V4grVIlD8gqfXQnz3ZxDc6Ecc/edit?hl=en#slide=id.g307db23881_0_305 (google internal only, sorry)

It overlaps quite a bit because we want to be doing away with the ASCII generating part.

We do intend on submitting it and move the generation to the client-side (instead of C++ generating ASCII).

OK, sounds good.

One use case we should ensure not to regress is being able to export the data when coordinating someone on bug reports. Right now, the use case is basically to ask people to copy-paste the output of that page and email or attach to bug reports.

I assume this won't work very well with a full HTML page. So I would suggest to instead add a button to export the data - and maybe keep the existing ascii format for that, since that likely would be easiest than inventing a new format.

I wasn't aware that other people were already working on it. Good to see that this page will be improved soon!

I agree with all what's said. My reaction to chrome://histograms as it is right now was pretty much 😱. I consider any improvement good to take on board.

In that regard, I'll promote my CL (https://chromium-review.googlesource.com/c/chromium/src/+/897385) for a couple of seconds:

Pros:
Cleans up things a bit
Doesn't really change the logic (still ASCII-based histograms)
Low risk
Ready right now
ASCII-based histograms are pretty robust, and can be copied-pasted-mailed.

Cons:
It's not ambitious (still ASCII-based histograms)
It might conflict with other efforts to modernize chrome://histograms

So, I'll let you decide whether you want to take it on board or not. Even if it is temporary, and get replaced by an awesome UI a bit later, I would consider it a progress.

It might even be complementary. We might still want to have an ASCII-based histogram report capability (for debugging or copy-paste-mail) and an awesome dynamic UI.

And yes, I also discovered the filtering feature (eg chrome://histograms/Security) by reading the C++ code...

I'd rather we go with a single change, rather than having some intermediate churn. We have some internal tools that parse the output, so any changes to the format would require some changes there, so if we know we're going to change the format again soon, I'd rather not go with the intermediate change.

So my suggestion is we wait for mathp's change and have that be the new version. If, for some reason, that doesn't pan out - then we can consider the other ones.

I noticed that at least one test (PolicyStatisticsCollectorTest.Startup in browser_tests) parses the output. This is pretty fragile.

I don't know if there are any other ones.

FYI, I recently added to the DevTools protocol two functions allowing to retrieve histograms.

https://chromedevtools.github.io/devtools-protocol/tot/Browser#method-getHistograms
https://chromedevtools.github.io/devtools-protocol/tot/Browser#method-getHistogram

This might be useful when replacing or upgrading tools parsing chrome://histograms.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/18170a49b39546ea32d21dc7d61bc82d61529fd0

commit 18170a49b39546ea32d21dc7d61bc82d61529fd0
Author: Mathieu Perreault <mathp@chromium.org>
Date: Thu May 17 12:48:15 2018

[Histograms] Revamp of the chrome://histograms page

Now a WebUI message handler. Still keeps the same UI
for now, but has potential to be more (see earlier patchsets)

Bug: 809820, 788270
Change-Id: I9e2de72540f152ad367098d8255492378bbb28a3
Reviewed-on: https://chromium-review.googlesource.com/890627
Reviewed-by: Avi Drissman <avi@chromium.org>
Reviewed-by: Julian Pastarmov <pastarmovj@chromium.org>
Reviewed-by: Bernhard Bauer <bauerb@chromium.org>
Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Commit-Queue: Mathieu Perreault <mathp@chromium.org>
Cr-Commit-Position: refs/heads/master@{#559504}
[modify] https://crrev.com/18170a49b39546ea32d21dc7d61bc82d61529fd0/chrome/browser/policy/policy_browsertest.cc
[modify] https://crrev.com/18170a49b39546ea32d21dc7d61bc82d61529fd0/content/browser/BUILD.gn
[delete] https://crrev.com/c70cdb314e37ae58980dd993433748d9c09e64dc/content/browser/histogram_internals_request_job.cc
[delete] https://crrev.com/c70cdb314e37ae58980dd993433748d9c09e64dc/content/browser/histogram_internals_request_job.h
[delete] https://crrev.com/c70cdb314e37ae58980dd993433748d9c09e64dc/content/browser/histogram_internals_url_loader.cc
[delete] https://crrev.com/c70cdb314e37ae58980dd993433748d9c09e64dc/content/browser/histogram_internals_url_loader.h
[add] https://crrev.com/18170a49b39546ea32d21dc7d61bc82d61529fd0/content/browser/histograms_internals_ui.cc
[add] https://crrev.com/18170a49b39546ea32d21dc7d61bc82d61529fd0/content/browser/histograms_internals_ui.h
[add] https://crrev.com/18170a49b39546ea32d21dc7d61bc82d61529fd0/content/browser/resources/histograms/histograms_internals.html
[add] https://crrev.com/18170a49b39546ea32d21dc7d61bc82d61529fd0/content/browser/resources/histograms/histograms_internals.js
[modify] https://crrev.com/18170a49b39546ea32d21dc7d61bc82d61529fd0/content/browser/webui/content_web_ui_controller_factory.cc
[modify] https://crrev.com/18170a49b39546ea32d21dc7d61bc82d61529fd0/content/browser/webui/url_data_manager_backend.cc
[modify] https://crrev.com/18170a49b39546ea32d21dc7d61bc82d61529fd0/content/browser/webui/web_ui_url_loader_factory.cc
[modify] https://crrev.com/18170a49b39546ea32d21dc7d61bc82d61529fd0/content/content_resources.grd

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/f38ba52d12bfbbff75397033b1a140b4ee3e7c4b

commit f38ba52d12bfbbff75397033b1a140b4ee3e7c4b
Author: Mathieu Perreault <mathp@chromium.org>
Date: Wed May 23 19:30:08 2018

[Histograms page] Create a build target for histograms internals JS

As well, address comments from
https://chromium-review.googlesource.com/c/chromium/src/+/890627

Bug: 809820, 788270
Change-Id: Idb11e6045ad79993792da08245485c3e64259f85
Reviewed-on: https://chromium-review.googlesource.com/1065576
Reviewed-by: calamity <calamity@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Commit-Queue: Mathieu Perreault <mathp@chromium.org>
Cr-Commit-Position: refs/heads/master@{#561202}
[modify] https://crrev.com/f38ba52d12bfbbff75397033b1a140b4ee3e7c4b/BUILD.gn
[add] https://crrev.com/f38ba52d12bfbbff75397033b1a140b4ee3e7c4b/content/browser/resources/BUILD.gn
[add] https://crrev.com/f38ba52d12bfbbff75397033b1a140b4ee3e7c4b/content/browser/resources/histograms/BUILD.gn
[add] https://crrev.com/f38ba52d12bfbbff75397033b1a140b4ee3e7c4b/content/browser/resources/histograms/OWNERS
[modify] https://crrev.com/f38ba52d12bfbbff75397033b1a140b4ee3e7c4b/content/browser/resources/histograms/histograms_internals.html
[modify] https://crrev.com/f38ba52d12bfbbff75397033b1a140b4ee3e7c4b/content/browser/resources/histograms/histograms_internals.js