<webview>: Partially migrate loadcommit event from content to chrome

chrome/browser/adview/adview_constants.h

+// Copyright 2013 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.
+
+// Constants used for the adview API.
+
+#ifndef CHROME_BROWSER_ADVIEW_ADVIEW_CONSTANTS_H_
+#define CHROME_BROWSER_ADVIEW_ADVIEW_CONSTANTS_H_
+
+namespace adview {
+
+// Events.
+extern const char kEventLoadCommit[];
+
+// Parameters/properties on events.
+extern const char kIsTopLevel[];
+extern const char kUrl[];
+
+// Attributes.
+extern const char kAttributeApi[];
+
+}  // namespace adview
+
+#endif  // CHROME_BROWSER_ADVIEW_ADVIEW_CONSTANTS_H_
+