@rhourieh: Could you please provide a sample test file or extension to check the issue from our end?

Thanks!!

Thank you for your reply. I'll prepare a sample test as I can't post the extension I'm working with.

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Waiting for reply as per C#2 to proceed.

Here's a sample reproducer extension.

Steps to reproduce the problem:
0. Unpack and load the extension into Chrome (v. 54 shows the gray area and it's easier to see)
1. Open chrome with a non-fullscreen mode. I used the command `GoogleChromePortable.exe --window-size=1024,768`
2. Navigate to a url of the page you want.
3. Click on the camera icon to the top right
** This will first apply the "Page.setDeviceMetricsOverride" then take a screenshot of that tab afterwards
** The screenshot will open in a new tab (which makes it easier to see the gray areas) and this is similar to what my original extension was doing.
4. If you repeat 1-3 but after changing the extension code to have `fitWindow: false` you see that the gray areas are gone.

I've tried the same with Chrome 59 the only difference is that the margin is white.

I'm not sure if this means there's a difference between the window size and the emulation device. 
In my original extension changing the parameter to mobile to true also seemed to solve this but I couldn't reproduce it with the current reproducible now.

Please let me know if you need more info. Thanks in advance.

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Able to reproduce the issue on Windows 10 with chrome #59.0.3071.115 but not on the latest stable #60.0.3112.78
Attaching the screenshot for reference.

rhourieh@ could you please update chrome to the latest stable version and let us know your observations.

Note: Issue is also observed on Mac 10.12.5 and Ubuntu 14.04 in present stable #60.0.3112.78 and also in earlier versions M45, M46 builds.

Thank You... 

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Thank you for your feedback. I've updated to chrome #60.0.3112.78 (Official Build) beta (64-bit) (cohort: Beta) and I still can reproduce the issue. 

The issue was first observed in Ubuntu 16.04.2 LTS with Chrome #54. I couldn't verify the behavior there with chrome #60 yet.

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Tested on Chrome Stable #60.0.3112.90 on Mac 10.12.5, Windows7 and Ubuntu 14.04 and able to reproduce the issue. However issue is not reproduced on latest Beta #61.0.3163.39 & Canary #62.0.3181.0.

Using the reverse bisect providing the bisect results,

Good Build:62.0.3163.0 (Revision:488528).
Bad Build:61.0.3162.0  (Revision:488073).

You are probably looking for a change made after 488471 (known good), but no later than 488472 (first known bad).

CHANGELOG URL:
The script might not always return single CL as suspect as some perf builds might get missing due to failure.
https://chromium.googlesource.com/chromium/src/+log/e51107e73a6f93cfb447d6f5b432c100ef31d309..cc099f72c9fe6f67590e70b2956e27a7b5e7ac38

Review ON: https://chromium-review.googlesource.com/572222

@pfeldman --  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 owner concerned.

Note: This issue seems to be similar to  issue 742990 

Thanks.

Attaching screenshot for reference for C#11.

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We do not support fitWindow anymore.

Since which version is fitWindow not supported?

It was done in https://chromium-review.googlesource.com/c/chromium/src/+/572222, which went into version 61.

Is there a replacement for fitToWindow? I can still see it in the devtools, but the API does not have something that would suggest there is a new way of doing this.
Do i need to calculate the scale myself and pass it in with the device metrics?

Unfortunately the API documentation is very generic and does not give any information on how the fitToWindow behavior can be achieved again. I have tried scale and devicescale, but did not manage to scale anything down.
"Emulation.setPageScaleFactor" didn't change anything either.

The "scale" parameter of Emulation.setDeviceMetricsOverride should work just fine in this case, but you'll have to calculate it yourself.

I debugged the developertools and figured out that it is necessary to set the screenWidth and screenHeight parameter and the scale value and then it worked fine.
Thanks