I was not able to move the touch selection handles using the mouse. I was using a Nexus 6P, Android M, 56.0.2920.0.

In my initial patch for  Issue 468806 , I was able to drag touch text selection handles using mouse. Pedro is right in #c1: this no longer works. May be switching over to ACTION_POINTER_DOWN caused it?

Update: as of today, I am able to make text selection highlight appear through mouse, but the selection handles don't show up.

Correction: I meant ACTION_BUTTON_PRESS instead of ACTION_POINTER_DOWN in #c4.

Selection handles are for adjusting selections with touch and I think we shouldn't show them when the user is interacting with mouse.  We can go ahead and hide them if already present when the mouse cursor moves.  I understand this is already the behavior on ChromeOS so we would just need to hook up/duplicate the same code.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/58aea4974d2230c5900f79d9d6344747033a6500

commit 58aea4974d2230c5900f79d9d6344747033a6500
Author: mustaq <mustaq@chromium.org>
Date: Wed Feb 22 18:55:59 2017

Fixed Android text selection by redefining |button| value.

The |button| field in WebPointerProperties (used in WebMouseEvent and
WebTouchPoint) follows the dom UI Events spec which is well-defined for
mousedown/up events and for single-button-presses in other events. For
Android WebMouseEvents (enabled recently), we initially set this value
following the PointerEvent spec (which covers the multi-button-press
case perfectly) then discovered that text selection is not working. We
also discovered a bunch of other functionalities that depend on UI
Events like assumptions.

This CL refines Android |button| field to match other platforms, thus
fixes text selection.

BUG= 666060 

Review-Url: https://codereview.chromium.org/2639623002
Cr-Commit-Position: refs/heads/master@{#452150}

[modify] https://crrev.com/58aea4974d2230c5900f79d9d6344747033a6500/content/browser/android/content_view_core_impl.cc
[modify] https://crrev.com/58aea4974d2230c5900f79d9d6344747033a6500/content/browser/android/content_view_core_impl.h
[modify] https://crrev.com/58aea4974d2230c5900f79d9d6344747033a6500/content/browser/renderer_host/input/web_input_event_builders_android.cc
[modify] https://crrev.com/58aea4974d2230c5900f79d9d6344747033a6500/content/browser/renderer_host/input/web_input_event_builders_android.h
[modify] https://crrev.com/58aea4974d2230c5900f79d9d6344747033a6500/content/browser/renderer_host/render_widget_host_view_android.cc
[modify] https://crrev.com/58aea4974d2230c5900f79d9d6344747033a6500/content/browser/renderer_host/render_widget_host_view_android.h
[modify] https://crrev.com/58aea4974d2230c5900f79d9d6344747033a6500/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
[modify] https://crrev.com/58aea4974d2230c5900f79d9d6344747033a6500/third_party/WebKit/public/platform/WebPointerProperties.h