Disable flaky DomDistillerViewerSourceBrowserTest.PrefChange test on Linux.

chrome/browser/dom_distiller/dom_distiller_viewer_source_browsertest.cc

Index: chrome/browser/dom_distiller/dom_distiller_viewer_source_browsertest.cc
diff --git a/chrome/browser/dom_distiller/dom_distiller_viewer_source_browsertest.cc b/chrome/browser/dom_distiller/dom_distiller_viewer_source_browsertest.cc
index 67a0372a511814c5379d5015ff3561a3f2d5c707..0fd6044220b5203c829aa7a8466f71d9cdd27459 100644
--- a/chrome/browser/dom_distiller/dom_distiller_viewer_source_browsertest.cc
+++ b/chrome/browser/dom_distiller/dom_distiller_viewer_source_browsertest.cc
@@ -524,7 +524,14 @@ IN_PROC_BROWSER_TEST_F(DomDistillerViewerSourceBrowserTest, MultiPageArticle) {
   EXPECT_THAT(result, HasSubstr("Page 2 content"));
 }
 
-IN_PROC_BROWSER_TEST_F(DomDistillerViewerSourceBrowserTest, PrefChange) {
+// Flaky on Ubuntu-12.04 bots: https://crbug.com/606037
+#if defined(OS_LINUX)
+#define MAYBE_PrefChange DISABLED_PrefChange
+#else
+#define MAYBE_PrefChange PrefChange
+#endif
+IN_PROC_BROWSER_TEST_F(DomDistillerViewerSourceBrowserTest,
+                       MAYBE_PrefChange) {
   PrefTest(false);
 }