[Android] Add AndroidSpellChecker feature to allow for gradual rollout using finch.

components/spellcheck/common/spellcheck_features.h

Index: components/spellcheck/common/spellcheck_features.h
diff --git a/components/spellcheck/common/spellcheck_features.h b/components/spellcheck/common/spellcheck_features.h
new file mode 100644
index 0000000000000000000000000000000000000000..ba0e2f2f8b435fbef948ed3f170cbf870433226b
--- /dev/null
+++ b/components/spellcheck/common/spellcheck_features.h
@@ -0,0 +1,21 @@
+// 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 COMPONENTS_SPELLCHECK_COMMON_SPELLCHECK_FEATURES_H_
+#define COMPONENTS_SPELLCHECK_COMMON_SPELLCHECK_FEATURES_H_
+
+#include "base/feature_list.h"
+
+namespace spellcheck {
+
+#if defined(ENABLE_SPELLCHECK) && defined(OS_ANDROID)
+extern const base::Feature kAndroidSpellChecker;
+extern const base::Feature kAndroidSpellCheckerNonLowEnd;

[Tobias Sargeant, 2016/08/30 10:39:52]

Not mentioned anywhere except here? I agree that being able to switch it off for
low end devices is a good idea (for the moment, at least) but maybe we should
just make that the behaviour of kAndroidSpellChecker?

[timvolodine, 2016/08/30 13:17:42]

yes, my idea was to be able to experiment with the AndroidSpellCheckerNonLowEnd
on our side to make it potentially not too disruptive for the users. While
having the global kAndroidSpellChecker feature for all other purposes. The
"NonLowEnd" could go away in the future when it's ready.

Admittedly I've probably been biased by
https://codereview.chromium.org/1508713002 in considering low-end devices as an
'early exit'. But it seems to make sense..

+
+bool IsAndroidSpellCheckFeatureEnabled();
+#endif  // defined(ENABLE_SPELLCHECK) && defined(OS_ANDROID)
+
+}  // namespace spellcheck
+
+#endif  // COMPONENTS_SPELLCHECK_COMMON_SPELLCHECK_FEATURES_H_