Tested in chrome #61.0.3163.79 and Canary #63.0.3212.0 on Mac 10.12.6 and not able to reproduce the issue.Please find the screen shots for your reference.

@ oliverzy: Could you please let me know if i have missed anything and if possible,Please create new profile without extensions and apps.Re-check once and let us know the observations and expected compressed size of the issue which would help us to triage the issue further.

Thanks in Advance.

Deleted: 763700.png 727 KB

	763700.png 727 KB View Download

The issue only seems to happen for the main html document resource, I marked it as red circle.
As you can see, it shows 76.1K.
However, if you check the Content-Length, it is actually less than 30K.

I attached another screenshot for you.

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	111.png 274 KB View Download

Thank you for providing more feedback. Adding requester "rbasuvula@chromium.org" to the cc list and removing "Needs-Feedback" label.

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

Tested in chrome Beta #61.0.3163.79 and canary #63.0.3213.0 on Mac 10.12.6,Ubuntu 14.04 & Win 7 able to reproduce the issue.
Unable to provide the per revision bisect and Normal bisect as getting all good builds even changing the bad range.So providing the manual bisect below are the Bisect Details:

Bisect Info:
=============
Good Build: 61.0.3163.0(Revision - 488528)
Bad Build: 62.0.3164.0(Revision - 488823)

CHANGELOG URL: https://chromium.googlesource.com/chromium/src/+log/61.0.3163.0..62.0.3164.0?pretty=fuller&n=10000
Suspect: https://chromium.googlesource.com/chromium/src/+/9e2bedd723e9a4a67e9623861de64c0e5d6d4d2f

From the CL above, assigning the issue to the concern owner

@eostroukhov: Could you please look into the issue, pardon me if it has nothing to do with your changes and if possible please assign it to concern owner.

Reviewed-On:https://chromium-review.googlesource.com/560602

Thank You!

This sounds like it's related to PlzNavigate (browser-side-navigation in about:flags).

If you're reproducing locally, make sure to turn on that flag.

I can verify that it's fixed without PlzNavigate, so it's a bug related to it.

I think it might be related to  https://crbug.com/760924 

 Issue 771167  has been merged into this issue.

 Issue 776322  has been merged into this issue.

More reports about gzip'ed size being wrong in  issue 776322 .

 Issue 775773  has been merged into this issue.

Bumping to P1.

As explained over email, we do have plans to change the delivery mechanic for the main resource in PlzNavigate. This is  issue 740130 . I do hope that it will fix this particular issue. However, while we're hoping to land in Q4, it may not arrive right away. So we might want to do a fix for the actual mechanism (ie with blob urls) to ensure this bug is fixed in the meantime.

FWIW, I think this can also cause things served from disk cache to not have (from disk cache) in the UI --- and likely also affects the resource timing API? 

 Issue 773762  has been merged into this issue.

According to a test ran by jeroenvdb on the WebPerformance slack channel [1] the same values are also present in Navigation Timing.

[1] https://webperformance.slack.com/files/U0PFN4K54/F7ZA8GBLK/picture_2017-11-13_at_17.08.02.jpg

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/81f89b3b8fbb90742d88ffef7d82a561cfee3c5b

commit 81f89b3b8fbb90742d88ffef7d82a561cfee3c5b
Author: Andrey Kosyakov <caseq@chromium.org>
Date: Mon Nov 13 19:52:45 2017

Associate actual response headers and undecoded size with streams

This associates original HttpRequestInfo and encoded data size
with Stream in the form of StreamMetadata, so that StreamURLRequestJob
could return actual values instead of the bogus ones that it currently
makes up.

This fixes a problem with reporting actual transferred bytes in
DevTools' network panel and removes the need for at last some of
the stream override params in WebURLLoaderImpl.

Bug:  763700 ,  705744 
Cq-Include-Trybots: master.tryserver.chromium.android:android_cronet_tester;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: I8493bbe464cd9a81a0864e5bcc9afd8b19aea3c5
Reviewed-on: https://chromium-review.googlesource.com/744290
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Pavel Feldman <pfeldman@chromium.org>
Reviewed-by: Takeshi Yoshino <tyoshino@chromium.org>
Reviewed-by: Matt Menke <mmenke@chromium.org>
Commit-Queue: Andrey Kosyakov <caseq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#516012}
[modify] https://crrev.com/81f89b3b8fbb90742d88ffef7d82a561cfee3c5b/content/browser/loader/stream_resource_handler.cc
[modify] https://crrev.com/81f89b3b8fbb90742d88ffef7d82a561cfee3c5b/content/browser/loader/stream_writer.cc
[modify] https://crrev.com/81f89b3b8fbb90742d88ffef7d82a561cfee3c5b/content/browser/loader/stream_writer.h
[modify] https://crrev.com/81f89b3b8fbb90742d88ffef7d82a561cfee3c5b/content/browser/streams/stream.cc
[modify] https://crrev.com/81f89b3b8fbb90742d88ffef7d82a561cfee3c5b/content/browser/streams/stream.h
[add] https://crrev.com/81f89b3b8fbb90742d88ffef7d82a561cfee3c5b/content/browser/streams/stream_metadata.h
[modify] https://crrev.com/81f89b3b8fbb90742d88ffef7d82a561cfee3c5b/content/browser/streams/stream_url_request_job.cc
[modify] https://crrev.com/81f89b3b8fbb90742d88ffef7d82a561cfee3c5b/content/browser/streams/stream_url_request_job.h
[modify] https://crrev.com/81f89b3b8fbb90742d88ffef7d82a561cfee3c5b/content/browser/streams/stream_url_request_job_unittest.cc
[modify] https://crrev.com/81f89b3b8fbb90742d88ffef7d82a561cfee3c5b/content/renderer/loader/web_url_loader_impl.cc
[modify] https://crrev.com/81f89b3b8fbb90742d88ffef7d82a561cfee3c5b/content/renderer/loader/web_url_loader_impl.h
[modify] https://crrev.com/81f89b3b8fbb90742d88ffef7d82a561cfee3c5b/net/url_request/url_request_job.cc
[modify] https://crrev.com/81f89b3b8fbb90742d88ffef7d82a561cfee3c5b/net/url_request/url_request_job.h
[modify] https://crrev.com/81f89b3b8fbb90742d88ffef7d82a561cfee3c5b/third_party/WebKit/LayoutTests/FlagExpectations/enable-features=NetworkService
[add] https://crrev.com/81f89b3b8fbb90742d88ffef7d82a561cfee3c5b/third_party/WebKit/LayoutTests/http/tests/inspector-protocol/network/navigation-xfer-size-expected.txt
[add] https://crrev.com/81f89b3b8fbb90742d88ffef7d82a561cfee3c5b/third_party/WebKit/LayoutTests/http/tests/inspector-protocol/network/navigation-xfer-size.js

this is huge. caseq, much thanks to making this fix happen!

is this something we could merge to 63?

IU'm sure there will be at lase _some_ merge conflicts, but still should be possible. Let it bake for some time on dev channel, we need to make sure it doesn't regress anything, then we'll see how bad the merge would be.

 Issue 785350  has been merged into this issue.

 Issue 787346  has been merged into this issue.

 Issue 787506  has been merged into this issue.