Upstream most of the iOS WebUI support in ios/web/

ios/public/provider/web/web_ui_ios_message_handler.h

Index: ios/public/provider/web/web_ui_ios_message_handler.h
diff --git a/ios/public/provider/web/web_ui_ios_message_handler.h b/ios/public/provider/web/web_ui_ios_message_handler.h
new file mode 100644
index 0000000000000000000000000000000000000000..133dc8280fec6eddaa7135b661169a9c539b0f27
--- /dev/null
+++ b/ios/public/provider/web/web_ui_ios_message_handler.h
@@ -0,0 +1,64 @@
+// Copyright 2014 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_PUBLIC_PROVIDER_WEB_WEB_UI_IOS_MESSAGE_HANDLER_H_
+#define IOS_PUBLIC_PROVIDER_WEB_WEB_UI_IOS_MESSAGE_HANDLER_H_
+
+#include "base/basictypes.h"
+#include "base/strings/string16.h"
+
+class GURL;
+
+namespace base {
+class DictionaryValue;
+class ListValue;
+}
+
+namespace web {
+
+class WebUIIOS;
+class WebUIIOSImpl;
+
+// Messages sent from the DOM are forwarded via the WebUIIOS to handler
+// classes. These objects are owned by WebUIIOS and destroyed when the
+// host is destroyed.
+class WebUIIOSMessageHandler {
+ public:
+  WebUIIOSMessageHandler() : web_ui_(NULL) {}
+  virtual ~WebUIIOSMessageHandler() {}
+
+ protected:
+  // Helper methods:
+
+  // Extract an integer value from a list Value.
+  static bool ExtractIntegerValue(const base::ListValue* value, int* out_int);
+
+  // Extract a floating point (double) value from a list Value.
+  static bool ExtractDoubleValue(const base::ListValue* value,
+                                 double* out_value);
+
+  // Extract a string value from a list Value.
+  static base::string16 ExtractStringValue(const base::ListValue* value);
+
+  // This is where subclasses specify which messages they'd like to handle and
+  // perform any additional initialization. At this point web_ui() will return
+  // the associated WebUIIOS object.
+  virtual void RegisterMessages() = 0;
+
+  // Returns the attached WebUIIOS for this handler.
+  WebUIIOS* web_ui() const { return web_ui_; }
+
+  // Sets the attached WebUIIOS - exposed to subclasses for testing purposes.
+  void set_web_ui(WebUIIOS* web_ui) { web_ui_ = web_ui; }
+
+ private:
+  // Provide external classes access to web_ui() and set_web_ui().
+  friend class WebUIIOSImpl;
+
+  WebUIIOS* web_ui_;
+};
+
+}  // namespace web
+
+#endif  // IOS_PUBLIC_PROVIDER_WEB_WEB_UI_IOS_MESSAGE_HANDLER_H_