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 /components/security_interstitials

This CL was uploaded by git cl split.

R=nparker@chromium.org

Bug: 1110266
Change-Id: I2a2fada6c9b7dd6b9f90c95be41eac72f30d4b3d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2370293
Auto-Submit: Sean McAllister <smcallis@google.com>
Reviewed-by: Nathan Parker <nparker@chromium.org>
Commit-Queue: Nathan Parker <nparker@chromium.org>
Cr-Commit-Position: refs/heads/master@{#801070}

components/security_interstitials/content/utils.cc

@@ -31,7 +31,7 @@ void LaunchDateAndTimeSettings() {
 #if defined(OS_ANDROID)
   JNIEnv* env = base::android::AttachCurrentThread();
   Java_DateAndTimeSettingsHelper_openDateAndTimeSettings(env);
-#elif defined(OS_LINUX)
+#elif defined(OS_LINUX) || defined(OS_CHROMEOS)
   struct ClockCommand {
     const char* const pathname;
     const char* const argument;