Fixed the problem at the source of the flaky WebViewTest.ShimArcAttribute test.

chrome/browser/apps/web_view_browsertest.cc

Index: chrome/browser/apps/web_view_browsertest.cc
diff --git a/chrome/browser/apps/web_view_browsertest.cc b/chrome/browser/apps/web_view_browsertest.cc
index 3bd83954c3d6eeaba5fbf496bc1a91fcf18bec19..4f61be54fe0a15ace1c49fda9611fd67e14b7ade 100644
--- a/chrome/browser/apps/web_view_browsertest.cc
+++ b/chrome/browser/apps/web_view_browsertest.cc
@@ -1254,13 +1254,7 @@ IN_PROC_BROWSER_TEST_F(WebViewTest, InterstitialTeardown) {
   window->GetBaseWindow()->Close();
 }
 
-#if defined(OS_LINUX)
-// http://crbug.com/431604
-#define MAYBE_ShimSrcAttribute DISABLED_ShimSrcAttribute
-#else
-#define MAYBE_ShimSrcAttribute ShimSrcAttribute
-#endif
-IN_PROC_BROWSER_TEST_F(WebViewTest, MAYBE_ShimSrcAttribute) {
+IN_PROC_BROWSER_TEST_F(WebViewTest, ShimSrcAttribute) {
   ASSERT_TRUE(RunPlatformAppTest("platform_apps/web_view/src_attribute"))
       << message_;
 }