refactor: replace USE_X11 with OS_LINUX for sharing code with Ozone

[c4rtune]

Description of Change

This pull-request is a small first step in trying to bring support for Wayland to Electron. I'm planning to follow up on this with more pull-requests in an effort to upstream these Wayland patches.

However, those patches will need some adjustments in order to make them compatible with the upcoming Chromium changes (chromium#1085700) which will soon be merged into Electron (#25488). In particular, it should be taken into consideration that the USE_X11 and USE_OZONE build flags are no longer mutually exclusive.

Also, USE_X11 is going away so it might be desirable as a long term goal to remove it from Electron too and replace it with the Ozone equivalents.

With that in mind, this pull-request replaces a few instances of #if defined(USE_X11) with #if defined(OS_LINUX) where it was identified that the guarded code could be shared with Ozone.

The more meaningful changes will come in the upcoming pull-requests but I'll be waiting for these chromium changes to be pulled into Electron first (#24984, #25488).

Checklist

• PR description included and stakeholders cc'd (@zcbenz @hedgepigdaniel)
• npm test passes
• PR title follows semantic commit guidelines

Release Notes

Notes: none

[MonnetalX]

🔍 PR Link Analysis

🔗 Ranked Links

#1 these Wayland patches

🔍 The referenced patches replace USE_X11 conditionals with OS_LINUX to enable sharing code between X11 and Wayland (Ozone) builds, which is the first step toward adding Wayland support to Electron.

#2 #25488

🔍 Replacing USE_X11 with OS_LINUX is a necessary step to enable sharing code with Ozone and support Wayland in Electron.

#3 going away

🔍 Replacing USE_X11 with OS_LINUX is a necessary step to enable Electron to support Wayland, which would improve rendering performance on embedded devices and modern Linux desktops.

#4 #24984

🔍 The referenced pull request is a Chromium version bump that serves as the baseline for the Wayland patches being upstreamed in this PR.

#5 commit guidelines

🔍 This pull request replaces USE_X11 with OS_LINUX to enable sharing code across X11 and Wayland backends in preparation for Wayland support.

#6 https://github.com/electron/electron/blob/master/CONTRIBUTING.md

🔍 This pull request is a small first step toward supporting Wayland in Electron by replacing USE_X11 with OS_LINUX to share code with Ozone.

#7 chromium#1085700

🔍 The webpage content is not available, but based on the PR context, this change replaces the USE_X11 preprocessor macro with OS_LINUX to enable sharing code between X11 and Ozone (Wayland) builds.

#8 these chromium changes

🔍 The Wayland patches referenced in the PR description are hosted on Gerrit Code Review, which is the platform used for reviewing and managing the code changes needed to add Wayland support to Electron.