Disable FrameNavigationEntry_NewSubframe on Linux due to flakes.

content/browser/frame_host/navigation_controller_impl_browsertest.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/frame_host/navigation_controller_impl.h"
 
 #include <stdint.h>
 #include <utility>
 
 #include "base/bind.h"
@@ skipping 2241 matching lines @@
         "   +--Site B ------- proxies for A\n"
         "        +--Site A -- proxies for B\n"
         "Where A = http://127.0.0.1/\n"
         "      B = http://foo.com/",
         visualizer.DepictFrameTree(root));
   }
 }
 
 // Verify the tree of FrameNavigationEntries after NAVIGATION_TYPE_NEW_SUBFRAME
 // commits.
+// Disabled due to flakes on Linux Tests; see https://crbug.com/646836.
+#if defined(OS_LINUX)
+#define MAYBE_FrameNavigationEntry_NewSubframe \
+    DISABLED_FrameNavigationEntry_NewSubframe
+#else
+#define MAYBE_FrameNavigationEntry_NewSubframe FrameNavigationEntry_NewSubframe
+#endif
 IN_PROC_BROWSER_TEST_F(NavigationControllerBrowserTest,
-                       FrameNavigationEntry_NewSubframe) {
+                       MAYBE_FrameNavigationEntry_NewSubframe) {
   GURL main_url(embedded_test_server()->GetURL(
       "/navigation_controller/simple_page_1.html"));
   NavigateToURL(shell(), main_url);
   const NavigationControllerImpl& controller =
       static_cast<const NavigationControllerImpl&>(
           shell()->web_contents()->GetController());
   FrameTreeNode* root =
       static_cast<WebContentsImpl*>(shell()->web_contents())->
           GetFrameTree()->root();
 
@@ skipping 3729 matching lines @@
       &headers));
 
   // Verify the Origin and Referer headers.
   EXPECT_THAT(headers, ::testing::HasSubstr("Origin: null"));
   EXPECT_THAT(headers,
               ::testing::ContainsRegex(
                   "Referer: http://a.com:.*/form_that_posts_cross_site.html"));
 }
 
 }  // namespace content