Revert of IPC::ParamTraits for ui::Event (towards ui::Events over mojo IPC)

ui/metro_viewer/metro_viewer_messages.h

Index: ui/metro_viewer/metro_viewer_messages.h
diff --git a/ui/metro_viewer/metro_viewer_messages.h b/ui/metro_viewer/metro_viewer_messages.h
index 72428f52a28a155537ffc93aeb8aec39ab6e2308..8dfab4dc771a579de74e716b2ddd2fa762544415 100644
--- a/ui/metro_viewer/metro_viewer_messages.h
+++ b/ui/metro_viewer/metro_viewer_messages.h
@@ -14,6 +14,22 @@
 #include "ui/metro_viewer/ime_types.h"
 
 #define IPC_MESSAGE_START MetroViewerMsgStart
+
+IPC_ENUM_TRAITS(ui::EventType)
+IPC_ENUM_TRAITS(ui::EventFlags)
+
+// Contains the parameters sent for a mousebutton message.
+IPC_STRUCT_BEGIN(MetroViewerHostMsg_MouseButtonParams)
+
+  IPC_STRUCT_MEMBER(int32_t, x)
+  IPC_STRUCT_MEMBER(int32_t, y)
+  IPC_STRUCT_MEMBER(int32_t, extra)
+  IPC_STRUCT_MEMBER(ui::EventType, event_type)
+  IPC_STRUCT_MEMBER(uint32_t, flags)
+  IPC_STRUCT_MEMBER(ui::EventFlags, changed_button)
+  IPC_STRUCT_MEMBER(bool, is_horizontal_wheel)
+
+IPC_STRUCT_END()
 
 // Messages sent from the viewer to the browser:
 
@@ -26,6 +42,9 @@
                      int32_t, /* x-coordinate */
                      int32_t, /* y-coordinate */
                      int32_t /* flags */)
+// Informs the brower that a mouse button was pressed.
+IPC_MESSAGE_CONTROL1(MetroViewerHostMsg_MouseButton,
+                     MetroViewerHostMsg_MouseButtonParams)
 // Informs the browser that a key was pressed.
 IPC_MESSAGE_CONTROL4(MetroViewerHostMsg_KeyDown,
                      uint32_t, /* virtual key */