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/browser/ui/views/drag_and_drop_interactive_uitest.cc

This CL was uploaded by git cl split.

R=falken@chromium.org

Bug: 1110266
Change-Id: Ieddb5edf2fe68a91f1eab897dc3706b3181dbe79
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2371260
Auto-Submit: Sean McAllister <smcallis@google.com>
Reviewed-by: Matt Falkenhagen <falken@chromium.org>
Commit-Queue: Matt Falkenhagen <falken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#800888}

chrome/browser/ui/views/drag_and_drop_interactive_uitest.cc

@@ -1036,7 +1036,7 @@ IN_PROC_BROWSER_TEST_P(DragAndDropBrowserTest, DragStartInFrame) {
 // There is no known way to execute test-controlled tasks during
 // a drag-and-drop loop run by Windows OS.
 #define MAYBE_DragImageBetweenFrames DISABLED_DragImageBetweenFrames
-#elif defined(OS_LINUX)
+#elif defined(OS_LINUX) || defined(OS_CHROMEOS)
 #define MAYBE_DragImageBetweenFrames DISABLED_DragImageBetweenFrames
 #else
 #define MAYBE_DragImageBetweenFrames DragImageBetweenFrames