Fix SyntheticPointerActionParams compile error for ipc fuzzer

content/common/input/synthetic_pointer_action_params.h

Index: content/common/input/synthetic_pointer_action_params.h
diff --git a/content/common/input/synthetic_pointer_action_params.h b/content/common/input/synthetic_pointer_action_params.h
index e5a9a9d48ce2e47b91ffc4b1eefeec6314b83cff..fe6c9f9b4a301b8a240fd1952ddc9893bc7efc53 100644
--- a/content/common/input/synthetic_pointer_action_params.h
+++ b/content/common/input/synthetic_pointer_action_params.h
@@ -11,6 +11,11 @@
 #include "content/common/input/synthetic_gesture_params.h"
 #include "ui/gfx/geometry/point_f.h"
 
+namespace ipc_fuzzer {
+template <class T>
+struct FuzzTraits;
+}  // namespace ipc_fuzzer
+
 namespace content {
 
 struct CONTENT_EXPORT SyntheticPointerActionParams
@@ -67,6 +72,7 @@ struct CONTENT_EXPORT SyntheticPointerActionParams
 
  private:
   friend struct IPC::ParamTraits<content::SyntheticPointerActionParams>;
+  friend struct ipc_fuzzer::FuzzTraits<content::SyntheticPointerActionParams>;
 
   PointerActionType pointer_action_type_;
   // Pass a position value when sending a press or move action.