C77 - "Distill page" button shows in omnibox

[bsclifton]

Test plan

Make sure the Distill page button (pictured below) does not show up on:

• public web sites
• internal pages
• guest window
• tor window
• different profiles

Description

Starting with Chromium 77, a "Distill page" button is shown in the omnibox

This is used to provide a reader view of a given page. However, when using on internal pages like brave://welcome, it breaks:

Steps to Reproduce

1. Have a build with Chromium 77 in it
2. Visit any page; verify Distill page button shows in omnibox
3. Visit brave://welcome
4. Click the Distill page button

Actual result:

Error (as pictured in description)

Expected result:

Either:

• no button
  OR
• don't show button on internal pages

Reproduces how often:

100%

[rebron]

Let's hide the distill button in all cases from the url bar.

[bridiver]

  // TODO(gilmanmh): Display icon for only those pages that are likely to
  // render well in Reader Mode.
  SetVisible(true);

I think we can do a chromium_src override of ReaderModeIconView in OmniboxPageActionIconContainerView and override Update to

bool ReaderModeIconView::Update() {
    SetVisible(false);
    return false;
 }

[petemill]

Reminder for myself and @bsclifton - this still needs uplift to 69, 70 and 71

[GeetaSarvadnya]

Verification passed on

Brave	0.68.134 Chromium: 77.0.3865.75 (Official Build) (64-bit)
Revision	201e747d032611c5f2785cae06e894cf85be7f8a-refs/branch-heads/3865@{#776}
OS	Windows 10 OS Version 1803 (Build 17134.523)

• Verified the test plan from Reader Mode: remove UI button brave-core#3397
• Verified the STR and test plan mentioned in the issue description

Verified passed with

Brave	0.68.134 Chromium: 77.0.3865.75 (Official Build) (64-bit)
Revision	201e747d032611c5f2785cae06e894cf85be7f8a-refs/branch-heads/3865@{#776}
OS	macOS Version 10.13.6 (Build 17G5019)

• Verified the test plan from Reader Mode: remove UI button brave-core#3397
• Verified the STR and test plan mentioned in the issue description

Verification passed on

Brave	0.68.134 Chromium: 77.0.3865.75 (Official Build) (64-bit)
Revision	201e747d032611c5f2785cae06e894cf85be7f8a-refs/branch-heads/3865@{#776}
OS	Ubuntu 18.04 LTS

• Verified the test plan from Reader Mode: remove UI button brave-core#3397
• Verified the STR and test plan mentioned in the issue description