Remove some global UI defines
Remove the USE_CLIPBOARD_AURAX11 C++ define which were unused. The use_clipboard_aurax11 build variable was only used in one place (ui/base/BUILD.gn) and seems not to be useful. This is replaced by a "use_x11 && is_desktop_linux" condition.
Remove the enable_clipboard_aurax11 build arg which affected the use_ variant above and is no longer needed.
Move USE_DEFAULT_RENDER_THEME build variable and C++ define to Blink's public features.
Review-Url: https://codereview.chromium.org/2498733002
Cr-Commit-Position: refs/heads/master@{#432010}
14 files changed
