Add macro for consistent logging when disabling tests.

ios/testing/earl_grey/disabled_test_macros.h

+// Copyright 2016 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.
+
+#ifndef IOS_TESTING_EARL_GREY_DISABLED_TEST_MACROS_H_
+#define IOS_TESTING_EARL_GREY_DISABLED_TEST_MACROS_H_
+
+// A macro that forces an Earl Grey test to pass. It should be used to disable
+// tests that fail due to a bug. This macro should be used when the
+// configuration for which the test should be disabled can only be determined
+// at runtime. Disabling at compile-time is always preferred.
+// Example:
+// - (void)testFoo
+// if (base::ios::IsRunningOnIOS10OrLater()) {
+//   EARL_GREY_TEST_DISABLED(@"Disabled on iOS 10.");
+// }
+#define EARL_GREY_TEST_DISABLED(message)                                \
+  while (true) {                                                        \
+    NSLog(@"-- Earl Grey Test Disabled -- %@", message);                \
+    return;                                                             \
+  }
+
+// A macro that forces an Earl Grey test to pass. This should be used when a
+// test fails for a specific configuration because it is not supported, but
+// there is no error. This macro should only be used when the configuration for
+// which the test should be disabled can only be determined at runtime.
+// Disabling at compile-time is always preferred.
+// Example:
+// - (void)testFoo
+// if (base::ios::IsRunningOnIOS10OrLater()) {
+//   EARL_GREY_TEST_SKIPPED(@"Test not supported on iOS 10.");
+// }
+#define EARL_GREY_TEST_SKIPPED(message)                                \
+  while (true) {                                                       \
+    NSLog(@"-- Earl Grey Test Skipped -- %@", message);                \
+    return;                                                            \
+  }
+
+#endif  // IOS_TESTING_EARL_GREY_DISABLED_TEST_MACROS_H_