Bug 1920197 - Add prefs to allow updating Widevine directly from the Chromium update service. r=media-playback-reviewers,alwu

This patch allows us to download Widevine updates directly from the
Chromium update service, bypassing balrog and fallback configuration
options. This will be useful in the early stages of testing Widevine
updates, allowing us to use whatever Google has pushed to its own users,
including beta updates, before we engage release engineering.

Relevant Widevine L3 prefs have been added:
- media.gmp-widevinecdm.force-chromium-update
- media.gmp-widevinecdm.force-chromium-beta

which force the use of the Chromium update service, and requesting beta
versions (if available) respectively.

Similarly, Widevine L1 prefs have been added as well:
- media.gmp-widevinecdm-l1.force-chromium-update
- media.gmp-widevinecdm-l1.force-chromium-beta

Differential Revision: https://phabricator.services.mozilla.com/D223017

UltraBlame original commit: 6b000b63a5884ae454a4f0273947afff299e171d

Author: marco-c

Diff for: browser/app/profile/firefox.js

@@ -24772,6 +24772,63 @@ media
 .
 gmp
 -
+manager
+.
+chromium
+-
+update
+-
+url
+"
+"
+https
+:
+/
+/
+update
+.
+googleapis
+.
+com
+/
+service
+/
+update2
+/
+crx
+?
+response
+=
+redirect
+&
+x
+=
+id
+%
+3D
+%
+GUID
+%
+%
+26uc
+&
+acceptformat
+=
+crx3
+&
+updaterversion
+=
+999
+"
+)
+;
+pref
+(
+"
+media
+.
+gmp
+-
 widevinecdm
 .
 visible
@@ -24793,6 +24850,60 @@ enabled
 true
 )
 ;
+pref
+(
+"
+media
+.
+gmp
+-
+widevinecdm
+.
+chromium
+-
+guid
+"
+"
+oimompecagnajdejgnnjijobebaeigek
+"
+)
+;
+pref
+(
+"
+media
+.
+gmp
+-
+widevinecdm
+.
+force
+-
+chromium
+-
+update
+"
+false
+)
+;
+pref
+(
+"
+media
+.
+gmp
+-
+widevinecdm
+.
+force
+-
+chromium
+-
+beta
+"
+false
+)
+;
 #
 if
 defined
@@ -24821,6 +24932,66 @@ forceInstall
 false
 )
 ;
+pref
+(
+"
+media
+.
+gmp
+-
+widevinecdm
+-
+l1
+.
+chromium
+-
+guid
+"
+"
+neifaoindggfcjicffkgpmnlppeffabd
+"
+)
+;
+pref
+(
+"
+media
+.
+gmp
+-
+widevinecdm
+-
+l1
+.
+force
+-
+chromium
+-
+update
+"
+false
+)
+;
+pref
+(
+"
+media
+.
+gmp
+-
+widevinecdm
+-
+l1
+.
+force
+-
+chromium
+-
+beta
+"
+false
+)
+;
 #
 ifdef
 NIGHTLY_BUILD