The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/a11f498ff6fd68256a6d37218b23074c847e0f37

commit a11f498ff6fd68256a6d37218b23074c847e0f37
Author: Drew Stonebraker <stonebraker@chromium.org>
Date: Mon Jan 07 20:45:20 2019

Disable autofill for WebView Shell url bar

Added importantForAutofill="no" attribute to url bar EditText.

Removed tools:ignore="Autofill" attribute from url bar, as it is now
obsolete. Also removed TODO comment for removing the lint ignore,
which referenced  issue 900912 .

  ninja build succeeded without lint error.

Bug:  916000 ,  900912 
Test: AutoFillManager no longer outputs to logcat on input focus.
Change-Id: Icfbdf9dad518505f3ed42e28bad774b5701aad93
Reviewed-on: https://chromium-review.googlesource.com/c/1381519
Reviewed-by: Nate Fischer <ntfschr@chromium.org>
Reviewed-by: Tim Volodine <timvolodine@chromium.org>
Reviewed-by: Changwan Ryu <changwan@chromium.org>
Reviewed-by: Tao Bai <michaelbai@chromium.org>
Commit-Queue: Drew Stonebraker <stonebraker@chromium.org>
Cr-Commit-Position: refs/heads/master@{#620457}
[modify] https://crrev.com/a11f498ff6fd68256a6d37218b23074c847e0f37/android_webview/tools/system_webview_shell/apk/res/layout/activity_webview_browser.xml

To verify this, 

after touch the url bar, you can dump autofill service, by run
adb shell dumpsys autofill

You shouldn't see the shell url bar trigger the autofill from history section of output.