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 /base/security_unittest.cc

This CL was uploaded by git cl split.

R=jln@chromium.org

Bug: 1110266
Change-Id: I2e4b59b6cfb69c0638f7effb5e5d5e8f79e49f5d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2371211Reviewed-by: danakj <danakj@chromium.org>
Commit-Queue: Sean McAllister <smcallis@google.com>
Cr-Commit-Position: refs/heads/master@{#803940}

base/security_unittest.cc

@@ -49,7 +49,7 @@ NOINLINE Type HideValueFromCompiler(volatile Type value) {
 // - USE_TCMALLOC (should be set if compiled with use_allocator=="tcmalloc")
 // - ADDRESS_SANITIZER it has its own memory allocator
 #if (defined(OS_LINUX) || defined(OS_CHROMEOS)) && BUILDFLAG(USE_TCMALLOC) && \
-  !defined(ADDRESS_SANITIZER)
+                              !defined(ADDRESS_SANITIZER)
 #define MALLOC_OVERFLOW_TEST(function) function
 #else
 #define MALLOC_OVERFLOW_TEST(function) DISABLED_##function