Prepare SyntheticPointerAction to handle touch actions for multiple fingers

content/browser/renderer_host/input/synthetic_pointer_action.h

Index: content/browser/renderer_host/input/synthetic_pointer_action.h
diff --git a/content/browser/renderer_host/input/synthetic_pointer_action.h b/content/browser/renderer_host/input/synthetic_pointer_action.h
index 23b23fa421be29b1254cd491eebcbaff13adbb06..ed35e0fc3e50b2e3fae1ecfb0552a8c5edd7af42 100644
--- a/content/browser/renderer_host/input/synthetic_pointer_action.h
+++ b/content/browser/renderer_host/input/synthetic_pointer_action.h
@@ -5,6 +5,7 @@
 #ifndef CONTENT_BROWSER_RENDERER_HOST_INPUT_SYNTHETIC_POINTER_ACTION_H_
 #define CONTENT_BROWSER_RENDERER_HOST_INPUT_SYNTHETIC_POINTER_ACTION_H_
 
+#include <array>
 #include "base/macros.h"
 #include "content/browser/renderer_host/input/synthetic_gesture.h"
 #include "content/browser/renderer_host/input/synthetic_gesture_target.h"
@@ -12,25 +13,42 @@
 #include "content/common/content_export.h"
 #include "content/common/input/synthetic_pointer_action_params.h"
 
+using blink::WebTouchEvent;
+
 namespace content {
 
 class CONTENT_EXPORT SyntheticPointerAction : public SyntheticGesture {
  public:
+  using IndexMap = std::array<int, WebTouchEvent::touchesLengthCap>;
+
   explicit SyntheticPointerAction(const SyntheticPointerActionParams& params);
-  SyntheticPointerAction(const SyntheticPointerActionParams& params,
-                         SyntheticPointer* synthetic_pointer);
+  SyntheticPointerAction(
+      const std::vector<SyntheticPointerActionParams>& param_list,
+      SyntheticPointer* synthetic_pointer,
+      IndexMap* index_map);
   ~SyntheticPointerAction() override;
 
   SyntheticGesture::Result ForwardInputEvents(
       const base::TimeTicks& timestamp,
       SyntheticGestureTarget* target) override;
 
-  void ForwardTouchOrMouseInputEvents(const base::TimeTicks& timestamp,
-                                      SyntheticGestureTarget* target);
+  SyntheticGesture::Result ForwardTouchOrMouseInputEvents(
+      const base::TimeTicks& timestamp,
+      SyntheticGestureTarget* target);
+
+  void SetSyntheticPointer(SyntheticPointer* synthetic_pointer) {
+    synthetic_pointer_ = synthetic_pointer;
+  }
 
  private:
-  SyntheticPointerActionParams params_;
+  // These three objects are owned by SyntheticPointerActionController, which
+  // will manage their lifetime by initiating them when it starts processing a
+  // pointer action sequence and resets them when finish.
+  std::vector<SyntheticPointerActionParams> param_list_;

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

This is currently being copied. Should this be a const ref?

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

We cannot, because there is another constructor explicit
SyntheticPointerAction(const SyntheticPointerActionParams& params) which does
not initialize the value of param_list_.

[tdresser, 2016/05/20 14:24:30]

Then perhaps we should pass a pointer?

Right now the comment about lifetimes is incorrect, because param_list_ is owned
by the SyntheticPointerAction, because it's a copy of the data in
SyntheticPointerActionController.

Another option would be to have a backpointer to the
SyntheticPointerActionController, but having 3 raw pointers here is probably
cleaner.

   SyntheticPointer* synthetic_pointer_;
+  IndexMap* index_map_;
+
+  SyntheticPointerActionParams params_;
 
   DISALLOW_COPY_AND_ASSIGN(SyntheticPointerAction);
 };