Upgrade from Chromium 77.0.3865.90 to Chromium 78.0.3904.50

[mkarolin]

QA tests:

This is a major Chromium version bump, please do full passes.

Affected areas:

• Top sites suggestions,
• Profile (avatar) menu
• Welcome screen
• Themes on Linux
• Crash reporting on Linux

[mkarolin]

mac_sdk_min = 10.14
min macOS = 10.13
Xcode 9.3 (9E145)

Visual Studio Versions:
'2017' ('15.0'),
'2019', ('16.0')

[bsclifton]

Uplift checklist

Let's make sure we have all the proper stuff uplifted

0.71.x

brave-browser

• Update from Chromium 77.0.3865.90 to Chromium 78.0.3904.50
• manually resolve Fixes b-c branch pinning. #6410 (put 0.71.x as branch name in package.json)

brave-core

• Upgrade patches from Chromium 77.0.3865.90 to Chromium 78.0.3904.50
• Disables notification triggers API.
• Remove Compat suffix from Preferences in xml files - Not in 0.71.x
• Disable Sync USS Bookmarks
• Update l10n XTB and messages.json for 78.0.3904.50.
• Re-enable BraveLayoutProvider for c78
• Fixes Tor avatar menu after c78 bump.

COMING SOON NOT MERGED

• WIP: Fixes hover card bubble chrome:// urls.

Uplift done/approved/merged with:

• (0.71.x / brave-browser) Update from Chromium 77.0.3865.90 to Chromium 78.0.3904.50 (0.71.x) #6471
• (0.71.x / brave-core) Upgrade patches from Chromium 77.0.3865.90 to Chromium 78.0.3904.50 (0.71.x) brave-core#3693

0.70.x

(copy the items from 0.71.x once finalized)

Uplift done/approved/merged with:

• (0.70.x / brave-browser) Update from Chromium 77.0.3865.90 to Chromium 78.0.3904.50 (0.70.x) #6473
• (0.70.x / brave-core) Upgrade patches from Chromium 77.0.3865.90 to Chromium 78.0.3904.50 (0.70.x) brave-core#3695

[GeetaSarvadnya]

Verification passed on

Brave	0.70.117 Chromium: 78.0.3904.50 (Official Build) (64-bit)
Revision	2accdc52c79976e264cd2694df6db31d1fccd8e8-refs/branch-heads/3904@{#658}
OS	Windows 10 OS Version 1803 (Build 17134.1006)

Verification passed on

Brave	0.70.117 Chromium: 78.0.3904.50 (Official Build) (64-bit)
Revision	2accdc52c79976e264cd2694df6db31d1fccd8e8-refs/branch-heads/3904@{#658}
OS	Ubuntu 18.04 LTS

Verification PASSED on macOS 10.14.6 x64 using the following build:

Brave	0.70.117 Chromium: 78.0.3904.50 (Official Build) (64-bit)
Revision	2accdc52c79976e264cd2694df6db31d1fccd8e8-refs/branch-heads/3904@{#658}
OS	macOS Version 10.14.6 (Build 18G95)

[LaurenWags]

Removing from release notes as this issue is superseded by #6508