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.

Bug: 1110266
Change-Id: Iebbe654853bebeb4af49c9cb793dae5938416f3f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2351374
Commit-Queue: Sean McAllister <[email protected]>
Reviewed-by: Drew Wilson <[email protected]>
Reviewed-by: Erik Chen <[email protected]>
Reviewed-by: Brandon Jones <[email protected]>
Reviewed-by: Becca Hughes <[email protected]>
Reviewed-by: Dale Curtis <[email protected]>
Reviewed-by: Mike Wittman <[email protected]>
Reviewed-by: David Roger <[email protected]>
Reviewed-by: Dirk Pranke <[email protected]>
Reviewed-by: Avi Drissman <[email protected]>
Cr-Commit-Position: refs/heads/master@{#799710}
diff --git a/chrome/browser/flag_descriptions.cc b/chrome/browser/flag_descriptions.cc
index 79a64fc..d09ffe6 100644
--- a/chrome/browser/flag_descriptions.cc
+++ b/chrome/browser/flag_descriptions.cc
@@ -4425,13 +4425,15 @@
 #endif  // defined(OS_WIN) || defined(OS_MAC) || defined(OS_LINUX) ||
         // defined(OS_CHROMEOS)
 
-#if defined(OS_WIN) || defined(OS_MAC) || defined(OS_LINUX)
+#if defined(OS_WIN) || defined(OS_MAC) || defined(OS_LINUX) || \
+    defined(OS_CHROMEOS)
 
 const char kDirectManipulationStylusName[] = "Direct Manipulation Stylus";
 const char kDirectManipulationStylusDescription[] =
     "If enabled, Chrome will scroll web pages on stylus drag.";
 
-#endif  // defined(OS_WIN) || defined(OS_MAC) || defined(OS_LINUX)
+#endif  // defined(OS_WIN) || defined(OS_MAC) || defined(OS_LINUX) ||
+        // defined(OS_CHROMEOS)
 
 #if defined(OS_WIN) || defined(OS_MAC) || defined(OS_CHROMEOS)