Set the unique_event_id when converting from TouchEvent to WebTouchEvent

content/common/input_messages.h

 // Copyright (c) 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.
 
 // IPC messages for input events and other messages that require processing in
 // order relative to input events.
 // Multiply-included message file, hence no include guard.
 
+#include "base/basictypes.h"
 #include "base/strings/string16.h"
 #include "content/common/content_export.h"
 #include "content/common/content_param_traits.h"
 #include "content/common/edit_command.h"
 #include "content/common/input/did_overscroll_params.h"
 #include "content/common/input/input_event.h"
 #include "content/common/input/input_event_ack_state.h"
 #include "content/common/input/input_param_traits.h"
 #include "content/common/input/synthetic_gesture_packet.h"
 #include "content/common/input/synthetic_gesture_params.h"
@@ skipping 84 matching lines @@
 IPC_STRUCT_TRAITS_BEGIN(content::SyntheticTapGestureParams)
   IPC_STRUCT_TRAITS_PARENT(content::SyntheticGestureParams)
   IPC_STRUCT_TRAITS_MEMBER(position)
   IPC_STRUCT_TRAITS_MEMBER(duration_ms)
 IPC_STRUCT_TRAITS_END()
 
 IPC_STRUCT_BEGIN(InputHostMsg_HandleInputEvent_ACK_Params)
   IPC_STRUCT_MEMBER(blink::WebInputEvent::Type, type)
   IPC_STRUCT_MEMBER(content::InputEventAckState, state)
   IPC_STRUCT_MEMBER(ui::LatencyInfo, latency)
   // TODO(jdduke): Use Optional<T> type to avoid heap alloc, crbug.com/375002.

[jdduke (slow), 2015/03/13 15:31:59]

So, for some time I've been meaning to make the ack a proper structure, with
different fields for different event types.

i.e., overscroll would be a field for scrollupdate/wheel, id would be a field
for touch events, etc... similar to how WebGestureEvent behaves. Not sure if it
makes sense to do it now, but it would ease the pain of adding event
type-specific ack metadata in the future.

   IPC_STRUCT_MEMBER(scoped_ptr<content::DidOverscrollParams>, overscroll)
+  IPC_STRUCT_MEMBER(uint64, unique_event_id)
 IPC_STRUCT_END()
 
 // Sends an input event to the render widget.
 IPC_MESSAGE_ROUTED3(InputMsg_HandleInputEvent,
                     IPC::WebInputEventPointer /* event */,
                     ui::LatencyInfo /* latency_info */,
                     bool /* is_keyboard_shortcut */)
 
 // Sends the cursor visibility state to the render widget.
 IPC_MESSAGE_ROUTED1(InputMsg_CursorVisibilityChange,
@@ skipping 143 matching lines @@
 // This IPC message sends the character bounds after every composition change
 // to always have correct bound info.
 IPC_MESSAGE_ROUTED2(InputHostMsg_ImeCompositionRangeChanged,
                     gfx::Range /* composition range */,
                     std::vector<gfx::Rect> /* character bounds */)
 
 // Adding a new message? Stick to the sort order above: first platform
 // independent InputMsg, then ifdefs for platform specific InputMsg, then
 // platform independent InputHostMsg, then ifdefs for platform specific
 // InputHostMsg.