Prepare SyntheticPointerAction to handle touch actions for multiple fingers

content/browser/renderer_host/input/synthetic_pointer_action_controller.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/browser/renderer_host/input/synthetic_pointer_action_controller.h"
+
+namespace content {
+
+SyntheticPointerActionController::SyntheticPointerActionController() {
+  for (size_t i = 0; i < index_map_.size(); ++i)
+    index_map_[i] = -1;
+}
+SyntheticPointerActionController::~SyntheticPointerActionController() {}
+
+std::unique_ptr<SyntheticGesture>
+SyntheticPointerActionController::CreateSyntheticPointerAction(
+    const SyntheticPointerActionParams& gesture_params) {
+  DCHECK(gesture_params.pointer_action_type() !=
+         SyntheticPointerActionParams::PointerActionType::NOT_INITIALIZED);
+  std::unique_ptr<SyntheticGesture> synthetic_gesture;
+  if (gesture_params.pointer_action_type() ==
+          SyntheticPointerActionParams::PointerActionType::PROCESS ||
+      gesture_params.pointer_action_type() ==
+          SyntheticPointerActionParams::PointerActionType::FINISH) {
+    if (gesture_params.pointer_action_type() ==

[tdresser, 2016/05/19 17:57:04]

Move this outside of the outer if. I think reducing the amount of nesting here
will make this easier to read.

[lanwei, 2016/05/20 01:48:16]

Done.

+        SyntheticPointerActionParams::PointerActionType::FINISH) {
+      action_param_list_.push_back(gesture_params);
+    }
+
+    // TODO(lanwei): Will support multiple pointer types in the same stream
+    // later.

[tdresser, 2016/05/19 17:57:04]

Add a bug link.

[lanwei, 2016/05/20 01:48:16]

Done.

+    if (!action_param_list_.empty()) {
+      if (!synthetic_pointer_)
+        SetSyntheticPointer(gesture_params);
+
+      synthetic_gesture =
+          std::unique_ptr<SyntheticGesture>(new SyntheticPointerAction(
+              action_param_list_, synthetic_pointer_.get(), &index_map_));
+      action_param_list_.clear();
+    }
+  } else

[tdresser, 2016/05/19 17:57:03]

Add {} here. In general if one clause of an if statement requires {}, it makes
sense to use them on all clauses.

+    action_param_list_.push_back(gesture_params);

[tdresser, 2016/05/19 17:57:03]

I'd invert this condition so the common, easy to follow case (pushing the
gesture params) comes first, and the complicated case (process || finish), comes
second.

[lanwei, 2016/05/20 01:48:16]

Done.

+  return synthetic_gesture;
+}
+
+void SyntheticPointerActionController::SetSyntheticPointer(
+    const SyntheticPointerActionParams& gesture_params) {
+  SyntheticGestureParams::GestureSourceType gesture_source_type =
+      gesture_params.gesture_source_type;
+  if (gesture_source_type == SyntheticGestureParams::DEFAULT_INPUT)
+    gesture_source_type = default_type_;
+  DCHECK_NE(gesture_source_type, SyntheticGestureParams::DEFAULT_INPUT);
+  synthetic_pointer_ = SyntheticPointer::Create(gesture_source_type);
+}
+
+void SyntheticPointerActionController::ResetSyntheticPointer() {
+  synthetic_pointer_.reset();
+}
+
+void SyntheticPointerActionController::SetDefaultGestureSourceType(
+    SyntheticGestureParams::GestureSourceType default_type) {
+  default_type_ = default_type;
+}
+
+int SyntheticPointerActionController::PointerIndex(int index) const {

[tdresser, 2016/05/19 17:57:04]

Do we need this method here? Could it be defined in
synthetic_gesture_controller_unittest.cc?

[lanwei, 2016/05/20 01:48:16]

Done.

+  CHECK_GE(index, 0);
+  CHECK_LT(index, WebTouchEvent::touchesLengthCap);
+  return index_map_[index];
+}
+
+}  // namespace content