Using the per-revision bisect providing the bisect results,
Good build: 56.0.2907.0 (Revision: 429169).
Bad build: 56.0.2908.0 (Revision: 429486).

You are probably looking for a change made after 429464 (known good), but no later than 429465 (first known bad).
CHANGELOG URL:
  https://chromium.googlesource.com/chromium/src/+log/be9e1f1ffc1e1d3287c7d994587446f9d7e703ee..63797594bc2bb93e645129b0c679081dc925ba5f

@dpapad -- 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.
Thank You.

I am not able to reproduce this. Also in Act_Exp_Search_Focus.png screenshot, I don't see the bug. Both icons seem non-focused to me. See attachment on how a focused icon looks like

With response to comment #2

Correction : 

Actual : After step 2, ‘Search’ icon is seen enabled (i.e search icon still glows) even when there is no input in the search box.

Expected : ‘Search’ icon should be disabled (i.e search icon should appear in faint color) when there is no input in the search box.

@dpapad : Sorry for the confusion and kindly review an attached screen shot on how a search icon looks after step 2. Thank you! 

Deleted: Search_icon.png 44.5 KB

	Search_icon.png 44.5 KB View Download

Yeah, I can reproduce this.

The current behavior is something like:

1. Click on search field. This sets 'showingSearch' to true, which turns the icon white
2. Type in text
3. Click outside search field. Search field blurs, but because there's text in it, it doesn't close and change the icon back to grey.
4. Set search text to ''. This does not change 'showingSearch' or the icon color.

I think we can probably make it so that in step 4 (at [1]), if we set the text to '' while the search field is not focused, then set 'showingSearch' to false. I don't think this would affect any other cases, but I'd have to check.

[1] https://cs.chromium.org/chromium/src/ui/webui/resources/cr_elements/cr_search_field/cr_search_field_behavior.js

Tested the issue on Latest Canary# 57.0.2926.0 on Windows, Mac and Linux and is still reproducible.
@dpapad - Could you please look into the issue and update.
Thanks in Advance.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d69fa965ea7ddc2e61c7701a6b209c1d5f8bccda

commit d69fa965ea7ddc2e61c7701a6b209c1d5f8bccda
Author: tsergeant <tsergeant@chromium.org>
Date: Thu Jan 19 01:00:44 2017

MD Settings: Fix label visibility in subpage search fields

In crrev.com/438430, CrSearchFieldBehavior was simplified, removing
compatibility with iron-input. However, iron-input was still used by
<settings-subpage-search> to control the visibility of the input field
label.

This CL adds a public 'hasSearchText' property to the common search
field behavior which does not require iron-input to compute. This allows
<settings-subpage-search> to remove its dependency on iron-input, while
also fixing two minor issues:
- The input field label on <settings-subpage-search> now reappears when
  the 'clear search' button is clicked.
- The search icon in <cr-toolbar-search-field> now appears unfocused
  when the search field is cleared while it is unfocused.

BUG= 665700 , 665307 , 634665 
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2586803002
Cr-Commit-Position: refs/heads/master@{#444578}

[modify] https://crrev.com/d69fa965ea7ddc2e61c7701a6b209c1d5f8bccda/chrome/browser/resources/md_downloads/crisper.js
[modify] https://crrev.com/d69fa965ea7ddc2e61c7701a6b209c1d5f8bccda/chrome/browser/resources/md_downloads/vulcanized.html
[modify] https://crrev.com/d69fa965ea7ddc2e61c7701a6b209c1d5f8bccda/chrome/browser/resources/md_history/app.crisper.js
[modify] https://crrev.com/d69fa965ea7ddc2e61c7701a6b209c1d5f8bccda/chrome/browser/resources/md_history/app.vulcanized.html
[modify] https://crrev.com/d69fa965ea7ddc2e61c7701a6b209c1d5f8bccda/chrome/browser/resources/settings/settings_page/settings_subpage_search.html
[modify] https://crrev.com/d69fa965ea7ddc2e61c7701a6b209c1d5f8bccda/chrome/test/data/webui/cr_elements/cr_toolbar_search_field_tests.js
[modify] https://crrev.com/d69fa965ea7ddc2e61c7701a6b209c1d5f8bccda/ui/webui/resources/cr_elements/cr_search_field/cr_search_field_behavior.js
[modify] https://crrev.com/d69fa965ea7ddc2e61c7701a6b209c1d5f8bccda/ui/webui/resources/cr_elements/cr_toolbar/cr_toolbar_search_field.html
[modify] https://crrev.com/d69fa965ea7ddc2e61c7701a6b209c1d5f8bccda/ui/webui/resources/cr_elements/cr_toolbar/cr_toolbar_search_field.js