UserGestureIndicator is a mess. Clean it up.

third_party/WebKit/Source/platform/UserGestureIndicator.h

 /*
  * Copyright (C) 2010 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 15 matching lines @@
 #ifndef UserGestureIndicator_h
 #define UserGestureIndicator_h
 
 #include "platform/PlatformExport.h"
 #include "wtf/Noncopyable.h"
 #include "wtf/RefCounted.h"
 #include "wtf/RefPtr.h"
 
 namespace blink {
 
-enum ProcessingUserGestureState {
-  DefinitelyProcessingNewUserGesture,
-  DefinitelyProcessingUserGesture,
-  PossiblyProcessingUserGesture,
-  DefinitelyNotProcessingUserGesture
-};
-
-class PLATFORM_EXPORT UserGestureToken : public RefCounted<UserGestureToken> {
-  WTF_MAKE_NONCOPYABLE(UserGestureToken);
-
- public:
-  UserGestureToken() {}
-  virtual ~UserGestureToken() {}
-  virtual bool hasGestures() const = 0;
-  virtual void setOutOfProcess() = 0;
-  virtual void setJavascriptPrompt() = 0;
-  virtual void setPauseInDebugger() = 0;
-};
-
 // Callback to be invoked when the state of a UserGestureIndicator is
 // used (only during the scope of a UserGestureIndicator, does
 // not flow with the UserGestureToken).  It's the responsibility of the
 // caller to ensure the UserGestureUtilizedCallback is kept alive as long
 // as the UserGestureIndicator it's used in.
 // Note that this doesn't currently track EVERY way in which the
 // state of a UserGesture can be read (sometimes it's just propagated
 // elsewhere, or otherwise read in a way that's hard to know if it will
 // actually be used), but should include the primary use cases.  Therefore
 // this is suitable mainly for diagnostics and measurement purposes.
 class PLATFORM_EXPORT UserGestureUtilizedCallback {
  public:
   virtual ~UserGestureUtilizedCallback() = default;
   virtual void userGestureUtilized() = 0;
 };
 
+class PLATFORM_EXPORT UserGestureToken : public RefCounted<UserGestureToken> {

[Rick Byers, 2016/10/11 18:00:19]

nit: since you're overhauling this, can you please add a comment briefly
describing the semantics of a UserGestureToken?  

[Nate Chapin, 2016/10/11 19:17:55]

Done.

+  WTF_MAKE_NONCOPYABLE(UserGestureToken);
+
+ public:
+  enum Status { NewGesture, PossiblyExistingGesture };
+  enum TimeoutPolicy { Default, OutOfProcess, HasPaused };
+
+  static PassRefPtr<UserGestureToken> create(
+      Status status = PossiblyExistingGesture) {
+    return adoptRef(new UserGestureToken(status));
+  }
+
+  ~UserGestureToken() {}
+  bool hasGestures();
+  void transferGestureTo(UserGestureToken*);
+  bool consumeGesture();
+  void setTimeoutPolicy(TimeoutPolicy);
+  void setUserGestureUtilizedCallback(UserGestureUtilizedCallback*);

[Rick Byers, 2016/10/11 18:00:19]

Add a comment describing the lifetime semantics for the callback (see below).

[Nate Chapin, 2016/10/11 19:17:55]

Done.

+  void userGestureUtilized();
+
+ private:
+  UserGestureToken(Status);
+
+  bool hasTimedOut() const;
+
+  size_t m_consumableGestures;
+  double m_timestamp;
+  TimeoutPolicy m_timeoutPolicy;
+  UserGestureUtilizedCallback* m_usageCallback;
+};
+
 class PLATFORM_EXPORT UserGestureIndicator final {
   USING_FAST_MALLOC(UserGestureIndicator);
   WTF_MAKE_NONCOPYABLE(UserGestureIndicator);
 
  public:
   // Returns whether a user gesture is currently in progress.
   // Does not invoke the UserGestureUtilizedCallback.  Consider calling
   // utilizeUserGesture instead if you know for sure that the return value
   // will have an effect.
   static bool processingUserGesture();
@@ skipping 11 matching lines @@
   static bool consumeUserGesture();
 
   static UserGestureToken* currentToken();
 
   // Reset the notion of "since load".
   static void clearProcessedUserGestureSinceLoad();
 
   // Returns whether a user gesture has occurred since page load.
   static bool processedUserGestureSinceLoad();
 
-  explicit UserGestureIndicator(ProcessingUserGestureState,
-                                UserGestureUtilizedCallback* = 0);
-  explicit UserGestureIndicator(PassRefPtr<UserGestureToken>,
-                                UserGestureUtilizedCallback* = 0);
+  explicit UserGestureIndicator(PassRefPtr<UserGestureToken>);
   ~UserGestureIndicator();
 
  private:
-  static ProcessingUserGestureState s_state;
-  static UserGestureIndicator* s_topmostIndicator;
   static bool s_processedUserGestureSinceLoad;
-  ProcessingUserGestureState m_previousState;
+  static UserGestureToken* s_rootToken;
+
   RefPtr<UserGestureToken> m_token;
-  UserGestureUtilizedCallback* m_usageCallback;
 };
 
 }  // namespace blink
 
 #endif