Disable MediaGalleriesPrivateApiTest.DeviceAttachDetachEvents on Linux official bot.

chrome/browser/extensions/api/media_galleries_private/media_galleries_private_apitest.cc

Index: chrome/browser/extensions/api/media_galleries_private/media_galleries_private_apitest.cc
diff --git a/chrome/browser/extensions/api/media_galleries_private/media_galleries_private_apitest.cc b/chrome/browser/extensions/api/media_galleries_private/media_galleries_private_apitest.cc
index aa2a715bc71e8ee619ee4e1e0fe66568ef3451c1..79edf1fa7cc86fd3972cea4760458137935bf540 100644
--- a/chrome/browser/extensions/api/media_galleries_private/media_galleries_private_apitest.cc
+++ b/chrome/browser/extensions/api/media_galleries_private/media_galleries_private_apitest.cc
@@ -106,7 +106,14 @@ class MediaGalleriesPrivateApiTest : public ExtensionApiTest {
   DISALLOW_COPY_AND_ASSIGN(MediaGalleriesPrivateApiTest);
 };
 
-IN_PROC_BROWSER_TEST_F(MediaGalleriesPrivateApiTest, DeviceAttachDetachEvents) {
+// Fails on official Linux bot. See http://crbug.com/315276
+#if defined(GOOGLE_CHROME_BUILD) && defined(OS_LINUX)
+#define MAYBE_DeviceAttachDetachEvents DISABLED_DeviceAttachDetachEvents
+#else
+#define MAYBE_DeviceAttachDetachEvents DeviceAttachDetachEvents
+#endif
+IN_PROC_BROWSER_TEST_F(MediaGalleriesPrivateApiTest,
+                       MAYBE_DeviceAttachDetachEvents) {
   // Setup.
   TestStorageMonitor::SyncInitialize();
   const extensions::Extension* extension =