Able to reproduce the issue on Mac 10.11.6 using chrome version 56.0.2902.0 

Bisect Information:
------------------------
You are probably looking for a change made after 422935 (known good), but no later than 422936 (first known bad).

CHANGELOG URL:
----------------
https://chromium.googlesource.com/chromium/src/+log/5030e7f661b95940dc80c6f101fedbbd9b77cbfc..6297569d8adad927261a5f2f26bb0ea1c1fdc0c9

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

@lushnikov - Could you please check whether this is caused with respect to your change, if not please help us in assigning it to the right owner.

Thanks!

That's actually due to the suggest box which shows the history entries; Joel - is this intended?

It's intentional to show history items, but I think its unintentional to disregard the window completions.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/78b653a1157f70d99fc1caff0277798ce314b2bd

commit 78b653a1157f70d99fc1caff0277798ce314b2bd
Author: einbinder <einbinder@chromium.org>
Date: Fri Oct 28 22:41:27 2016

DevTools: Console now autocompletes on window for empty string

BUG= 659982 

Review-Url: https://codereview.chromium.org/2455273002
Cr-Commit-Position: refs/heads/master@{#428529}

[modify] https://crrev.com/78b653a1157f70d99fc1caff0277798ce314b2bd/third_party/WebKit/Source/devtools/front_end/console/ConsolePrompt.js

Tested this issue in Ubuntu 14.04 using chrome latest Dev M56-56.0.2908.0 by following steps mentioned in the original comment and observing different behavior. 

In steps-2 after hitting back space the expected behavior should be blank, But now it shows "$" sign with few other suggestions.

einbinder@ - Could you please confirm is this is the expected behavior for this issue?

Deleted: DevTools 281 KB

DevTools 281 KB View Download

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/84eec56141ead73f870bc436fc4cf49037cb481c

commit 84eec56141ead73f870bc436fc4cf49037cb481c
Author: einbinder <einbinder@chromium.org>
Date: Sat Nov 05 07:58:26 2016

DevTools: Distinguish between forced and unforced autocomplete in CMTE

Ctrl+Space is now considered a "force" autocomplete.
This is consistent with what we do in TextPrompt.

BUG= 659982 

Review-Url: https://codereview.chromium.org/2478923003
Cr-Commit-Position: refs/heads/master@{#430158}

[modify] https://crrev.com/84eec56141ead73f870bc436fc4cf49037cb481c/third_party/WebKit/Source/devtools/front_end/console/ConsolePrompt.js
[modify] https://crrev.com/84eec56141ead73f870bc436fc4cf49037cb481c/third_party/WebKit/Source/devtools/front_end/text_editor/CodeMirrorTextEditor.js
[modify] https://crrev.com/84eec56141ead73f870bc436fc4cf49037cb481c/third_party/WebKit/Source/devtools/front_end/text_editor/TextEditorAutocompleteController.js
[modify] https://crrev.com/84eec56141ead73f870bc436fc4cf49037cb481c/third_party/WebKit/Source/devtools/front_end/ui/TextEditor.js

Verified the issue on Windows 7, Ubuntu 14.04 and Mac 10.11.6 using Chrome Dev#56.0.2922.0 as per the comment #0.

Observed that the fix is working as expected.

Attaching the screencast for reference

Hence, adding the verified labels

Deleted: 659982.mp4 320 KB

	659982.mp4 320 KB View Download

Does this require a merge, Issue is labeled with M55. Could someone please take a look into it. Issue is already verified on M56 as per above comment.

Thanks.!

einbinder@ Tested this issue on chrome latest M55-55.0.2883.70 and observed the issue is still able to repro. Since this issue got fixed on chrome M-56, could you please merge the same to M-55.

Thanks!

@einbinder: Gentle ping, Issue is marked with M55 milestone, Can we have a merge request if required. Issue is fixed and verified already in M56.

Kindly update us on the same.

Thanks.!

einbinder@ Gentle Ping! Could you please respond for the comment #11.

Thanks!

einbinder@ Gentle Ping! Could you please respond for the comment #11.

Thanks!