Able to reproduce the issue on Mac 10.11.5 using 54.0.2806.0.

Note:
1.Will update win behavior soon
2.Attaching Expected Video for reference

Manual good and Bad Builds:
Good Build: 54.0.2804.0
Bad Build:  54.0.2805.0

Below is the Tool Bisect Info:

CHANGELOG URL:
https://chromium.googlesource.com/chromium/src/+log/59441af612e4c6922a412b22a783cf8cae3cdcf6..4b34e4b56319572e06425dd77e4d3b30d86ce049

Suspecting https://codereview.chromium.org/2168223002  from changelog

@pfeldman : Please feel free to re-assign if its not related to your change

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	Actual_ColorPicker.png 187 KB View Download

Deleted: Expected_ColorPicker.ogv 1.0 MB

	Expected_ColorPicker.ogv 1.0 MB View Download

Deleted: Expected_ColorPicker.png 219 KB

	Expected_ColorPicker.png 219 KB View Download

Issue is seen on Windows OS also

Adding Beta Blocker as this is a Recent Regression on M54.
Please feel free to remove if not required

Can repro on Windows version 54.0.2805.0 canary, I can work on this issue.

After having a deep investigation, I found this bug have existed before the commit https://codereview.chromium.org/2168223002. But not being exposed. The root case is:
In function "reposition" of SwatchPopoverHelper, "showView" of Popover is called (https://cs.chromium.org/chromium/src/third_party/WebKit/Source/devtools/front_end/ui/SwatchPopoverHelper.js?q=SwatchPopoverHelper.js&sq=package:chromium&dr&l=73). So, when we want to re-position the widget, the "showView" is executed more then one time. I am planning to prepare 2 CLs to solve this problem.
(1) ensure we can only call the show function once (https://codereview.chromium.org/2186833002).
(2) add a new function to do the reposition, like the Dialog.js does.(https://cs.chromium.org/chromium/src/third_party/WebKit/Source/devtools/front_end/ui/Dialog.js?q=Dialog.js&sq=package:chromium&dr&l=118)

pfeldman@ what's your opinion? thanks!

 Issue 631283  has been merged into this issue.

I noticed a CL was landed (https://codereview.chromium.org/2180853003), but it leads to another  issue 631890 . 

The root cause of these two issues (630920&631890) is that the Popover is to be shown more then one time. At the current logic, the previous Popover will be hidden first, then to show the new one, which means the previous one will be removed from the DOM tree directly without being notified (actually, the widget is the content of the popover, please seehttps://cs.chromium.org/chromium/src/third_party/WebKit/Source/devtools/front_end/ui/Popover.js?sq=package:chromium&dr&l=107). If these two popovers are different, everything is OK. But when the two popovers are exact the same one, the this._visible of this widget goes wrong. Even now we reparent the widget, that what the cl 2180853003 does, the status here (https://cs.chromium.org/chromium/src/third_party/WebKit/Source/devtools/front_end/ui/Widget.js?sq=package:chromium&dr&l=259) is still wrong. After being hidden, the this._visible should equal to "false", but the real value is "true", which results that this._processWillShow()&this._processWasShown() are never called.

The key is that we must call "hide()" of the Widget, if we want to hide it. We MUST prevent a widget from being removed directly, like this bug. My solution is simply and followed this principle. If the "show()" is called again when the widget is sill visible, just return. I think this behavior is reasonable and general. Please view the CL at https://codereview.chromium.org/2186833002

P.S. Another solution is that when the popover is being hidden, just call the content widget's hide method (we must keep a handle of the content widget), this will correct the internal visibility property in time.