Refactor OS_LINUX preprocessor directive for LaCrOS effort.

Currently, ChromeOS defines the OS_LINUX directive as well as
OS_CHROMEOS.  We're working to separate these two, so we're
making the fact that OS_LINUX == OS_LINUX || OS_CHROMEOS
explicit.

This is changes for /chrome/test/data/webui/settings

This CL was uploaded by git cl split.

R=dschuyler@chromium.org

Bug: 1110266
Change-Id: I3f47d833cdd11223ffad0240c2b815a80e4d0506
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2370287Reviewed-by: dpapad <dpapad@chromium.org>
Commit-Queue: Sean McAllister <smcallis@google.com>
Cr-Commit-Position: refs/heads/master@{#803985}

chrome/test/data/webui/settings/cr_settings_v3_browsertest.js

@@ -382,7 +382,7 @@ var CrSettingsSiteDetailsV3Test = class extends CrSettingsV3BrowserTest {
 // Disabling on debug due to flaky timeout on Win7 Tests (dbg)(1) bot.
 // https://crbug.com/825304 - later for other platforms in crbug.com/1021219.
 // Disabling on Linux CFI due to flaky timeout (crbug.com/1031960).
-GEN('#if (!defined(NDEBUG)) || (defined(OS_LINUX) && defined(IS_CFI))');
+GEN('#if (!defined(NDEBUG)) || ((defined(OS_LINUX) || defined(OS_CHROMEOS)) && defined(IS_CFI))');
 GEN('#define MAYBE_SiteDetails DISABLED_SiteDetails');
 GEN('#else');
 GEN('#define MAYBE_SiteDetails SiteDetails');