Add ContentSuggestion, ContentSuggestionCategory and ContentSuggestionProviderType

components/ntp_snippets/snippet_provider_type.h

Index: components/ntp_snippets/snippet_provider_type.h
diff --git a/components/ntp_snippets/snippet_provider_type.h b/components/ntp_snippets/snippet_provider_type.h
new file mode 100644
index 0000000000000000000000000000000000000000..7b0ee0490c78c772d221cc84cfbf6d0c23b9c458
--- /dev/null
+++ b/components/ntp_snippets/snippet_provider_type.h
@@ -0,0 +1,19 @@
+// 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_NTP_SNIPPETS_SNIPPET_PROVIDER_TYPE_H_
+#define COMPONENTS_NTP_SNIPPETS_SNIPPET_PROVIDER_TYPE_H_
+
+namespace ntp_snippets {
+
+// A type of snippet provider. For each of these types, there will be at most
+// one provider instance registered and running. Note that these provider types
+// do not necessarily match the snippet categories. The provider type is used
+// to identify the source of a snippet and to direct calls from the UI  like

[Marc Treib, 2016/06/13 15:11:10]

nit: extra space between "UI" and "like"

[Philipp Keck, 2016/06/13 15:27:50]

Done.

+// discarding back to the right provider.
+enum class SnippetProviderType : int { ARTICLES, OFFLINE_PAGES };
+
+}  // namespace ntp_snippets
+
+#endif  // COMPONENTS_NTP_SNIPPETS_SNIPPET_PROVIDER_TYPE_H_