Add SyntheticPointerActionParams used in Chromedriver extension

content/common/input/synthetic_pointer_action_params.cc

+// 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.
+
+#include "content/common/input/synthetic_pointer_action_params.h"
+
+namespace content {
+
+SyntheticPointerActionParams::SyntheticPointerActionParams()
+    : pointer_action_type_(PointerActionType::NOT_INITIALIZED), index_(-1) {}
+
+SyntheticPointerActionParams::SyntheticPointerActionParams(
+    PointerActionType type)
+    : pointer_action_type_(type), index_(-1) {}
+
+SyntheticPointerActionParams::SyntheticPointerActionParams(
+    const SyntheticPointerActionParams& other)
+    : SyntheticGestureParams(other),
+      pointer_action_type_(other.pointer_action_type()) {
+  switch (other.pointer_action_type()) {

[dcheng, 2016/03/31 20:04:37]

I'm curious why we can't just default this ctor: does it really matter that we
don't copy position_ if PointerActionType::RELEASE? It's still going to be
initialized to a known value.

[dcheng, 2016/04/02 08:05:11]

Ping? I'm still curious about the answer to this question.

[lanwei, 2016/04/02 14:51:21]

We are using SyntheticPointerActionParams to warp arguments passed from
chromedriver_extension. For the user input from chromedriver_extension, when the
type is RELEASE, it does not have a position information. If the type is
PROCESS, it does not have index and position values. This is why we add
constraints to the members' set and get function to avoid to set or use
inappropriate values. 

Maybe in this constructor, we can just copy this position_ value from other
object, but in general, we want to restrict when to set and get position and
index based on the type. 

+    case PointerActionType::PRESS:
+    case PointerActionType::MOVE:
+      index_ = other.index();
+      position_ = other.position();
+      break;
+    case PointerActionType::RELEASE:
+      index_ = other.index();
+      break;
+    default:
+      break;
+  }
+}
+
+SyntheticPointerActionParams::~SyntheticPointerActionParams() {}
+
+SyntheticGestureParams::GestureType
+SyntheticPointerActionParams::GetGestureType() const {
+  return POINTER_ACTION;
+}
+
+const SyntheticPointerActionParams* SyntheticPointerActionParams::Cast(
+    const SyntheticGestureParams* gesture_params) {
+  DCHECK(gesture_params);
+  DCHECK_EQ(POINTER_ACTION, gesture_params->GetGestureType());
+  return static_cast<const SyntheticPointerActionParams*>(gesture_params);
+}
+
+}  // namespace content