Last cleanup for BUILDFLAG(IS_OZONE)

Remove a few last references to USE_OZONE and add some comments

Bug: 1377327
Change-Id: I5ded6ff38b61828c4c076872e0a83110c9dfd6c5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4103982
Commit-Queue: Kyle Charbonneau <kylechar@chromium.org>
Reviewed-by: Thomas Anderson <thomasanderson@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1088892}

build/build_config.h

@@ -26,6 +26,9 @@
 
 // This file also adds defines specific to the platform, architecture etc.
 //
+//  Platform:
+//    IS_OZONE
+//
 //  Compiler:
 //    COMPILER_MSVC / COMPILER_GCC
 //

build/config/BUILD.gn

@@ -60,6 +60,9 @@ config("feature_flags") {
     defines += [ "USE_GLIB=1" ]
   }
   if (use_ozone && !is_android) {
+    # Chrome code should check BUILDFLAG(IS_OZONE) instead of
+    # defined(USE_OZONE).
+    #
     # Note that some Chrome OS builds unconditionally set |use_ozone| to true,
     # but they also build some targets with the Android toolchain. This ensures
     # that Android targets still build with USE_OZONE=0 in such cases.

chrome/browser/profiles/profile_browsertest.cc

@@ -530,7 +530,7 @@ IN_PROC_BROWSER_TEST_F(ProfileBrowserTest, MAYBE_ProfileReadmeCreated) {
 }
 
 // The EndSession IO synchronization is only critical on Windows, but also
-// happens under the USE_OZONE define. See BrowserProcessImpl::EndSession.
+// happens under Ozone. See BrowserProcessImpl::EndSession.
 #if BUILDFLAG(IS_WIN) || BUILDFLAG(IS_OZONE)
 
 namespace {

docs/ozone_overview.md

@@ -71,7 +71,7 @@ applications on the host system using a system clipboard mechanism.
 Our implementation of Ozone required changes concentrated in these areas:
 
 * Cleaning up extensive assumptions about use of X11 throughout the tree,
-  protecting this code behind the `USE_X11` ifdef, and adding a new `USE_OZONE`
+  protecting this code behind the `USE_X11` ifdef, and adding a new `IS_OZONE`
   path that works in a relatively platform-neutral way by delegating to the
   interfaces described above.
 * a `WindowTreeHostOzone` to send events into Aura and participate in display

ui/events/event.h

@@ -767,7 +767,7 @@ class EVENTS_EXPORT TouchEvent : public LocatedEvent {
 //    Japanese, etc. all use VKEY_Q for the key beside Tab, while French uses
 //    VKEY_A. The stored key_code_ is non-located (e.g. VKEY_SHIFT rather than
 //    VKEY_LSHIFT, VKEY_1 rather than VKEY_NUMPAD1).
-// -- |uint32_t scan_code_| [USE_OZONE only] supports remapping of the top
+// -- |uint32_t scan_code_| [IS_OZONE only] supports remapping of the top
 //    function row based on a sysfs attribute provided by the kernel. This
 //    allows devices to have a custom top row layout and still be able to
 //    perform translation back and forth between F-Key and Action-Key. The