Disable all the browser_tests that are flaking more than 5% of the time on trybots.

chrome/browser/extensions/extension_tabs_apitest.cc

Index: chrome/browser/extensions/extension_tabs_apitest.cc
diff --git a/chrome/browser/extensions/extension_tabs_apitest.cc b/chrome/browser/extensions/extension_tabs_apitest.cc
index bcb3d42667a0993e9660fedd259be9031fba7315..48a4b3463a9b37fa5d90f5c5f40e04e5d6bbe802 100644
--- a/chrome/browser/extensions/extension_tabs_apitest.cc
+++ b/chrome/browser/extensions/extension_tabs_apitest.cc
@@ -76,7 +76,13 @@ IN_PROC_BROWSER_TEST_F(ExtensionApiTest, TabSize) {
   ASSERT_TRUE(RunExtensionSubtest("tabs/basics", "tab_size.html")) << message_;
 }
 
-IN_PROC_BROWSER_TEST_F(ExtensionApiTest, TabUpdate) {
+// Flaky on linux: http://crbug.com/396364
+#if defined(OS_LINUX)
+#define MAYBE_TabUpdate DISABLED_TabUpdate
+#else
+#define MAYBE_TabUpdate TabUpdate
+#endif
+IN_PROC_BROWSER_TEST_F(ExtensionApiTest, MAYBE_TabUpdate) {
   ASSERT_TRUE(RunExtensionSubtest("tabs/basics", "update.html")) << message_;
 }