I agree.

Correct video attached.

Deleted: accounting_error.mp4 3.6 MB

	accounting_error.mp4 3.6 MB View Download

I think there are two parts to this bug:

1. If there isn't network activity, the values shown should be the same. They're queried slightly differently, so I verified that the underlying bytes we get are the same and that the string formatter doesn't have a rounding error (we use different format calls for the footer and settings menu). We may have an accounting bug that I haven't been able to reproduce. Bruno, do you have a concrete way to reproduce this?

2. The data savings may go up if there's network activity from the time when you open the context menu until you click on the footer. I don't think we should change this and think the user should get the higher savings value, since that is the most up-to-date data savings.

Yup, this is what this has looked like for me all day. I browsed bit, the values haven't converged.

I've found the problem. This is due to the interpolation done by the NetworkStatsHistory that we use on the settings page: https://cs.chromium.org/chromium/src/third_party/android_tools/sdk/sources/android-25/android/net/NetworkStatsHistory.java?rcl=cb6bc21107001e2f2eeee2707b482b2b755baf51&l=503

Are we ok with removing this interpolation? This means the integer values shown on the settings page will include the full bytes for the starting date bucket. I don't see any problem with this. 

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/46e542d6522f4508b6139269c40fbca018a6efdb

commit 46e542d6522f4508b6139269c40fbca018a6efdb
Author: megjablon <megjablon@chromium.org>
Date: Sat May 13 00:34:42 2017

Don't interpolate data use and saving values

Data Saver statistics should display total bytes since the start date,
not an interpolated value.

BUG= 720379 

Review-Url: https://codereview.chromium.org/2875863002
Cr-Commit-Position: refs/heads/master@{#471508}

[modify] https://crrev.com/46e542d6522f4508b6139269c40fbca018a6efdb/chrome/android/java/src/org/chromium/chrome/browser/preferences/datareduction/DataReductionStatsPreference.java

Your change meets the bar and is auto-approved for M59. Please go ahead and merge the CL to branch 3071 manually. Please contact milestone owner if you have questions.
Owners: amineer@(Android), cmasso@(iOS), gkihumba@(ChromeOS), Abdul Syed@(Desktop)

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d30c28c0bc4e4e02fb2db5dfb9e34009d7254ace

commit d30c28c0bc4e4e02fb2db5dfb9e34009d7254ace
Author: Megan Jablonski <megjablon@google.com>
Date: Mon May 15 19:26:05 2017

Don't interpolate data use and saving values

Data Saver statistics should display total bytes since the start date,
not an interpolated value.

BUG= 720379 

Review-Url: https://codereview.chromium.org/2875863002
Cr-Original-Commit-Position: refs/heads/master@{#471508}
Review-Url: https://codereview.chromium.org/2885473003 .
Cr-Commit-Position: refs/branch-heads/3071@{#563}
Cr-Branched-From: a106f0abbf69dad349d4aaf4bcc4f5d376dd2377-refs/heads/master@{#464641}

[modify] https://crrev.com/d30c28c0bc4e4e02fb2db5dfb9e34009d7254ace/chrome/android/java/src/org/chromium/chrome/browser/preferences/datareduction/DataReductionStatsPreference.java