[Picture-in-Picture] Disable SurfaceIdChangeDoesNotMoveWindow on Linux

This CL makes sure PictureInPictureWindowControllerBrowserTest
SurfaceIdChangeDoesNotMoveWindow test is disabled on Linux while we're
investigating the reason why.

Bug: 1146047
Change-Id: I4b0579109f2ebfe71ba786df471b86237d027384
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2521613Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
Commit-Queue: Mounir Lamouri <mlamouri@chromium.org>
Cr-Commit-Position: refs/heads/master@{#825010}

chrome/browser/picture_in_picture/picture_in_picture_window_controller_browsertest.cc

@@ -1334,8 +1334,14 @@ IN_PROC_BROWSER_TEST_F(PictureInPictureWindowControllerBrowserTest,
 
 // Tests that when a new surface id is sent to the Picture-in-Picture window, it
 // doesn't move back to its default position.
+// TODO(crbug.com/1146047): Test is flaky on Linux.
+#if defined(OS_LINUX)
+#define MAYBE_SurfaceIdChangeDoesNotMoveWindow DISABLED_SurfaceIdChangeDoesNotMoveWindow
+#else
+#define MAYBE_SurfaceIdChangeDoesNotMoveWindow SurfaceIdChangeDoesNotMoveWindow
+#endif
 IN_PROC_BROWSER_TEST_F(PictureInPictureWindowControllerBrowserTest,
-                       SurfaceIdChangeDoesNotMoveWindow) {
+                       MAYBE_SurfaceIdChangeDoesNotMoveWindow) {
   LoadTabAndEnterPictureInPicture(
       browser(), base::FilePath(kPictureInPictureWindowSizePage));