Able to reproduce the issue on the latest canary(63.0.3236.0) on Mac OS 10.12.6, worked fine on Windows-10, following the below test steps:

1. Changed the system timezone of Mac laptop to Australia EDT.
2. Sent one message to self and compared the time of the gmail with system time.
3. There is 1 hr diff b/w system and gmail message time.

This is a regression issue broken in M-63.

Last good build: 63.0.3212.0
First bad build: 63.0.3213.0

Changelog:
https://chromium.googlesource.com/chromium/src/+log/af92ddb997a848f65fa5d8d2c4a77b4ca809427b..0fc0c41c701aecd6c10a16927f4706beae7a50f8

Suspecting: https://chromium-review.googlesource.com/c/v8/v8/+/625164.

jshin@: Could you please take a look at this. 

ajha@:  What version of macOS was used to reproduce this issue? 

Is it macOS 10.12 or macOS 10.13 ? 

If it's macOS 10.13, it'll be fixed in  bug 754053  . 

Oh.. I missed this line:

> canary(63.0.3236.0) on Mac OS 10.12.6,

Just to make sure, can you go to the terminal and run the following command and post the output? 


ls -l /etc/localtime 

Thank you !

The following revision refers to this bug:
  https://chromium.googlesource.com/v8/v8.git/+/28ef8dc7009d57de2782668ed00dff34e31dee2d

commit 28ef8dc7009d57de2782668ed00dff34e31dee2d
Author: Jungshik Shin <jshin@chromium.org>
Date: Wed Oct 11 23:21:37 2017

Revert "Enable icu-timezone-data by default"

This reverts commit d9a25842d3aba82ead5e06c7fd7cb4896e6ad202.

Reason for revert: 

I'm reverting this CL for a few reasons. #2 is the most significant and I should have thought of that before making a switch. Sorry for that.   

1) perf-regression:  http://crbug.com/769706 
2)  http://crbug.com/612010  : ICU timezone update is not propagated to zygote process so that new tabs will hold on to an old timezone even after a timezone change on Linux and Chrome OS. 
3)  http://crbug.com/754053  : OS timezone detection issues on macOS 10.13, Ubutu 16, RHEL 7, SuSe Linux 12 or newer. ; it's being fixed. So, it actually ok.  
4)  http://crbug.com/771868  : timezone wrong in gmail: If it's due to #3, we're fine because it's fixed. If not, we need to look more.

Original change's description:
> Enable icu-timezone-data by default
> 
> This will introduce a new behavior on POSIX(-like) platforms. Timezone
> names inside parentheses after GMT offset will not be 3-4 letter
> abbreviation any longer. They'll be human-readable names in the current
> default locale. This matches the current Windows behavior.
> 
> new Date(2017, 5, 22).toString()
> new Date(2017, 11, 22).toString()
> 
> Current:
> 
> Thu Jun 22 2017 00:00:00 GMT-0700 (PDT)
> Fri Dec 22 2017 00:00:00 GMT-0800 (PST)
> 
> New in en-US locale:
> 
> Thu Jun 22 2017 00:00:00 GMT-0700 (Pacific Daylight Time)
> Fri Dec 22 2017 00:00:00 GMT-0800 (Pacific Standard Time)
> 
> New in German locale:
> 
> Thu Jun 22 2017 00:00:00 GMT-0700 (Nordamerikanische Westküsten-Sommerzeit)
> Fri Dec 22 2017 00:00:00 GMT-0800 (Nordamerikanische Westküsten-Normalzeit)
> 
> BUG= v8:6031 ,  v8:2137 , v8:6076
> TEST=mjsunit/icu-date-lord-howe.js, mjsunit/icu-date-to-string.js
> 
> Change-Id: I4e7fd8b3ddae5c7779e220c4c101e45904fcdc01
> Reviewed-on: https://chromium-review.googlesource.com/625164
> Commit-Queue: Jungshik Shin <jshin@chromium.org>
> Reviewed-by: Daniel Ehrenberg <littledan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#47953}

TBR=adamk@chromium.org,littledan@chromium.org,jshin@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug:  v8:6031 ,  v8:2137 , v8:6076,  chromium:769706 ,  chromium:612010 ,  chromium:771868 
Change-Id: I60d75467ee21975d3a235344b01c0d2d44a7da96
Reviewed-on: https://chromium-review.googlesource.com/713404
Reviewed-by: Adam Klein <adamk@chromium.org>
Commit-Queue: Jungshik Shin <jshin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48478}
[modify] https://crrev.com/28ef8dc7009d57de2782668ed00dff34e31dee2d/src/flag-definitions.h

Please make sure that this is merged back to 6.3 (as already mentioned in related issues) next week.

And removing blocker.

On macOS 10.12.16 with Chrome 63.0.3236.0, I can't reproduce this issue. 

Google Chrome	63.0.3236.0 (Official Build) dev (64-bit)
Revision	2fa96eead8c5eea003b5b7fb4f9262b3d136d76b-refs/heads/master@{#507286}
OS	Mac OS X
JavaScript	V8 6.3.272

> 1. Changed the system timezone of Mac laptop to Australia EDT.
> 2. Sent one message to self and compared the time of the gmail with system time.
> 3. There is 1 hr diff b/w system and gmail message time.

After sending an email to yourself, did you reload the gmail or did you open a new tab and go to gmail?   

If I just reload the gmail tab, the gmail time and the OS time are in agreement. 
If I open a new tab and go to gmail, there's one hour difference. 


In a new tab (opened after a timezone change), I got this. Note that timeZone is not defined. 

> var nf= new Intl.DateTimeFormat("en")

> nf.resolvedOptions()
{locale: "en", numberingSystem: "latn", calendar: "gregory", timeZone: undefined, year: "numeric", …}

In an existing tab, I got this (note that timeZOne is correct) 

{locale: "en", numberingSystem: "latn", calendar: "gregory", timeZone: "Australia/Sydney", year: "numeric", …}

Hmm.... this is  bug 612010 , but that bug didn't exist on macOS. It's only for Chrome OS and Linux. So, something must have happened recently to make it an issue on macOS.

Does macOS now have a zygote process?   

Deleted: Screen Shot 2017-10-12 at 10.43.12 PM.png 26.3 KB

	Screen Shot 2017-10-12 at 10.43.12 PM.png 26.3 KB View Download

Just to update and reply to the above comments:
C#5> Output from the terminal is: lrwxr-xr-x  1 root  wheel  36 Oct 12 23:00 /etc/localtime -> /usr/share/zoneinfo/Australia/Sydney

C#10> 
1. Changed the system timezone to Sydney and restarted the system.
2. Opened chrome canary(63.0.3238.0) and the latest stable(61.0.3163.100) and sent email to self.
3. Observing 1 hr diff. on canary and no diff. on stable.

There is no effect of reloading the gmail tab or opening gmail again in new tab for me on Chrome canary, but the same works fine on stable. 

No zygote on macOS.

Thanks, Mark and ajha@. 

Hmm... ajha's result in comment 11 is different from mine. 

Restarting the OS (that is not necessary) shouldn't make any difference. 

With the OS timezone set to Sydney, can you try the following?

1) Open DOM Inspector and go to 'Console' tab
2) Type the following:

(new Intl.DateTimeFormat("en")).resolvedOptions()

BTW, a new canary build (not the one you tried in comment 11 but what's coming up) may have a revert CL (see comment 6) so that it won't reproduce the bug. 

A more reliable way is to try the latest dev channel build. 

-----------------

What I reported in comment 10 is actually different from  bug 612010  in that timeZone is 'undefined' as oppose to holding the old value in a new tab. I think I know how to make it at least 'defined'.  It may take me a while to try that out (my mac desktop is still unavailable...)

No reason to have R-V-G. Making it public. 

As for Merge-approved-63, I thought I had landed the revert CL before M63 branch  cut. I'll check and if I didn't make it, I'll merge. 

> There is no effect of reloading the gmail tab 

What happens you do this? 

1) Set the timezone in something other than Australia/Sydney 
2) Start Chrome
3) Send an email to yourself in gmail and check the time stamp and compare with the OS time
4) Change the OS timezone to Australia/Sydney 
5) Reload the gmail tab
6) Check the timestamp of the email you sent in step 3 and compare it with the OS time

Filed  bug 774376  for the root cause. 

This bug is now fixed by reverting recorded in comment 6. 

Should be fixed when the latest canary picks up this change. 

re comment 14: because this is a v8 change, I need to merge the fix to v8's branch that goes with Chrome's 63 branch. I'll do. 

 bug 773532  is likely to be the real root cause.  Even with icu-timezone-data enabled in v8 (which was reverted in a CL recorded in comment 6), it's likely that we'd not have had this issue. 

However, I'm not certain without actually trying various combinations with my local build.

** Bulk Edit **

Please merge your change to M63 branch 3239 before 5:00 PM PT Monday (10/16) so we can take it in for next dev release. Thank you.

This issue has been approved for a merge. Please merge the fix to any appropriate branches as soon as possible!

If all merges have been completed, please remove any remaining Merge-Approved labels from this issue.

Thanks for your time! To disable nags, add the Disable-Nags label.

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/v8/v8.git/+/d7343703bc6a3c1dbd5ead201186c520ffc9e47b

commit d7343703bc6a3c1dbd5ead201186c520ffc9e47b
Author: Jungshik Shin <jshin@chromium.org>
Date: Mon Oct 16 20:43:16 2017

Merged: Revert "Enable icu-timezone-data by default"

This reverts commit d9a25842d3aba82ead5e06c7fd7cb4896e6ad202.
This is for 6.3 branch (to go with Chromium 63 branch). 

Reason for revert:

I'm reverting this CL for a few reasons. #2 is the most significant and
I should have thought of that before making a switch. Sorry for that.

1) perf-regression:  http://crbug.com/769706 
2)  http://crbug.com/612010  : ICU timezone update is not propagated to
zygote process so that new tabs will hold on to an old timezone even
after a timezone change on Linux and Chrome OS.

3)   http://crbug.com/754053   : OS timezone detection issues on macOS
10.13, Ubutu 16, RHEL 7, SuSe Linux 12 or newer. ; it's being fixed. So,
it actually ok.

4)   http://crbug.com/771868   : timezone wrong in gmail: If it's due to

Revision: 28ef8dc7009d

BUG= chromium:612010 , chromium:769706 , chromium:771868 , v8:2137 , v8:6031 ,v8:6076
LOG=N
NOTRY=true
NOPRESUBMIT=true
NOTREECHECKS=true
R=adamk@chromium.org, hablich@chromium.org

Change-Id: Id0093c2bc69e5bc1d3b7147b7bbcc633ed625a45
Reviewed-on: https://chromium-review.googlesource.com/721919
Reviewed-by: Adam Klein <adamk@chromium.org>
Commit-Queue: Jungshik Shin <jshin@chromium.org>
Cr-Commit-Position: refs/branch-heads/6.3@{#7}
Cr-Branched-From: 094a7c93dcdcd921de3883ba4674b7e1a0feffbe-refs/heads/6.3.292@{#1}
Cr-Branched-From: 18b8fbb528a8021e04a029e06eafee50b918bce0-refs/heads/master@{#48432}
[modify] https://crrev.com/d7343703bc6a3c1dbd5ead201186c520ffc9e47b/src/flag-definitions.h

Per comment #21, this is already merged to M63.

The following revision refers to this bug:
  https://chromium.googlesource.com/v8/v8.git/+/3b1cfa38bcd616609f263ac3b6721c0214c45d19

commit 3b1cfa38bcd616609f263ac3b6721c0214c45d19
Author: Michael Hablich <hablich@chromium.org>
Date: Tue Oct 17 16:11:43 2017

Revert "Merged: Revert "Enable icu-timezone-data by default""

This reverts commit d7343703bc6a3c1dbd5ead201186c520ffc9e47b.

Reason for revert: broke some branch builders like https://build.chromium.org/p/client.v8.branches/builders/V8%20arm%20-%20sim%20-%20beta%20branch%20-%20debug

Original change's description:
> Merged: Revert "Enable icu-timezone-data by default"
> 
> This reverts commit d9a25842d3aba82ead5e06c7fd7cb4896e6ad202.
> This is for 6.3 branch (to go with Chromium 63 branch). 
> 
> Reason for revert:
> 
> I'm reverting this CL for a few reasons. #2 is the most significant and
> I should have thought of that before making a switch. Sorry for that.
> 
> 1) perf-regression:  http://crbug.com/769706 
> 2)  http://crbug.com/612010  : ICU timezone update is not propagated to
> zygote process so that new tabs will hold on to an old timezone even
> after a timezone change on Linux and Chrome OS.
> 
> 3)   http://crbug.com/754053   : OS timezone detection issues on macOS
> 10.13, Ubutu 16, RHEL 7, SuSe Linux 12 or newer. ; it's being fixed. So,
> it actually ok.
> 
> 4)   http://crbug.com/771868   : timezone wrong in gmail: If it's due to
> 
> Revision: 28ef8dc7009d
> 
> BUG= chromium:612010 , chromium:769706 , chromium:771868 , v8:2137 , v8:6031 ,v8:6076
> LOG=N
> NOTRY=true
> NOPRESUBMIT=true
> NOTREECHECKS=true
> R=​adamk@chromium.org, hablich@chromium.org
> 
> Change-Id: Id0093c2bc69e5bc1d3b7147b7bbcc633ed625a45
> Reviewed-on: https://chromium-review.googlesource.com/721919
> Reviewed-by: Adam Klein <adamk@chromium.org>
> Commit-Queue: Jungshik Shin <jshin@chromium.org>
> Cr-Commit-Position: refs/branch-heads/6.3@{#7}
> Cr-Branched-From: 094a7c93dcdcd921de3883ba4674b7e1a0feffbe-refs/heads/6.3.292@{#1}
> Cr-Branched-From: 18b8fbb528a8021e04a029e06eafee50b918bce0-refs/heads/master@{#48432}

TBR=adamk@chromium.org,hablich@chromium.org,jshin@chromium.org

Change-Id: I8b30f8f9c63b93cb000facbf910ed111ca3f9ab2
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug:  chromium:612010 ,  chromium:769706 ,  chromium:771868 ,  v8:2137 ,  v8:6031 , v8:6076
Reviewed-on: https://chromium-review.googlesource.com/723324
Reviewed-by: Michael Hablich <hablich@chromium.org>
Commit-Queue: Michael Hablich <hablich@chromium.org>
Cr-Commit-Position: refs/branch-heads/6.3@{#18}
Cr-Branched-From: 094a7c93dcdcd921de3883ba4674b7e1a0feffbe-refs/heads/6.3.292@{#1}
Cr-Branched-From: 18b8fbb528a8021e04a029e06eafee50b918bce0-refs/heads/master@{#48432}
[modify] https://crrev.com/3b1cfa38bcd616609f263ac3b6721c0214c45d19/src/flag-definitions.h

The following revision refers to this bug:
  https://chromium.googlesource.com/v8/v8.git/+/9685d9c25a45f7902fe6250b64ca61abeea1e9f5

commit 9685d9c25a45f7902fe6250b64ca61abeea1e9f5
Author: Jungshik Shin <jshin@chromium.org>
Date: Tue Oct 17 20:55:47 2017

Revert "Revert "Merged: Revert "Enable icu-timezone-data by default"""

This reverts commit 3b1cfa38bcd616609f263ac3b6721c0214c45d19.

Reason for revert: ICU was not rolled in 6.3 branch leading invalid-locale test failure (that was added to test an ICU fix). Now, ICU is rolled in 6.3 branch ( https://chromium-review.googlesource.com/c/v8/v8/+/723564 ). 

Original change's description:
> Revert "Merged: Revert "Enable icu-timezone-data by default""
> 
> This reverts commit d7343703bc6a3c1dbd5ead201186c520ffc9e47b.
> 
> Reason for revert: broke some branch builders like https://build.chromium.org/p/client.v8.branches/builders/V8%20arm%20-%20sim%20-%20beta%20branch%20-%20debug
> 
> Original change's description:
> > Merged: Revert "Enable icu-timezone-data by default"
> > 
> > This reverts commit d9a25842d3aba82ead5e06c7fd7cb4896e6ad202.
> > This is for 6.3 branch (to go with Chromium 63 branch). 
> > 
> > Reason for revert:
> > 
> > I'm reverting this CL for a few reasons. #2 is the most significant and
> > I should have thought of that before making a switch. Sorry for that.
> > 
> > 1) perf-regression:  http://crbug.com/769706 
> > 2)  http://crbug.com/612010  : ICU timezone update is not propagated to
> > zygote process so that new tabs will hold on to an old timezone even
> > after a timezone change on Linux and Chrome OS.
> > 
> > 3)   http://crbug.com/754053   : OS timezone detection issues on macOS
> > 10.13, Ubutu 16, RHEL 7, SuSe Linux 12 or newer. ; it's being fixed. So,
> > it actually ok.
> > 
> > 4)   http://crbug.com/771868   : timezone wrong in gmail: If it's due to
> > 
> > Revision: 28ef8dc7009d
> > 
> > BUG= chromium:612010 , chromium:769706 , chromium:771868 , v8:2137 , v8:6031 ,v8:6076
> > LOG=N
> > NOTRY=true
> > NOPRESUBMIT=true
> > NOTREECHECKS=true
> > R=​adamk@chromium.org, hablich@chromium.org
> > 
> > Change-Id: Id0093c2bc69e5bc1d3b7147b7bbcc633ed625a45
> > Reviewed-on: https://chromium-review.googlesource.com/721919
> > Reviewed-by: Adam Klein <adamk@chromium.org>
> > Commit-Queue: Jungshik Shin <jshin@chromium.org>
> > Cr-Commit-Position: refs/branch-heads/6.3@{#7}
> > Cr-Branched-From: 094a7c93dcdcd921de3883ba4674b7e1a0feffbe-refs/heads/6.3.292@{#1}
> > Cr-Branched-From: 18b8fbb528a8021e04a029e06eafee50b918bce0-refs/heads/master@{#48432}
> 
> TBR=adamk@chromium.org,hablich@chromium.org,jshin@chromium.org
> 
> Change-Id: I8b30f8f9c63b93cb000facbf910ed111ca3f9ab2
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Bug:  chromium:612010 ,  chromium:769706 ,  chromium:771868 ,  v8:2137 ,  v8:6031 , v8:6076
> Reviewed-on: https://chromium-review.googlesource.com/723324
> Reviewed-by: Michael Hablich <hablich@chromium.org>
> Commit-Queue: Michael Hablich <hablich@chromium.org>
> Cr-Commit-Position: refs/branch-heads/6.3@{#18}
> Cr-Branched-From: 094a7c93dcdcd921de3883ba4674b7e1a0feffbe-refs/heads/6.3.292@{#1}
> Cr-Branched-From: 18b8fbb528a8021e04a029e06eafee50b918bce0-refs/heads/master@{#48432}

TBR=adamk@chromium.org,hablich@chromium.org,jshin@chromium.org

Change-Id: I8f712f1e6eb1f14c703ffe9f1d63d23b4b4bb08e
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug:  chromium:612010 ,  chromium:769706 ,  chromium:771868 ,  v8:2137 ,  v8:6031 , v8:6076
Reviewed-on: https://chromium-review.googlesource.com/723962
Reviewed-by: Michael Hablich <hablich@chromium.org>
Reviewed-by: Adam Klein <adamk@chromium.org>
Commit-Queue: Jungshik Shin <jshin@chromium.org>
Cr-Commit-Position: refs/branch-heads/6.3@{#21}
Cr-Branched-From: 094a7c93dcdcd921de3883ba4674b7e1a0feffbe-refs/heads/6.3.292@{#1}
Cr-Branched-From: 18b8fbb528a8021e04a029e06eafee50b918bce0-refs/heads/master@{#48432}
[modify] https://crrev.com/9685d9c25a45f7902fe6250b64ca61abeea1e9f5/src/flag-definitions.h