Implement complete lifecycle transition for IdleSpellCheckCallback

third_party/WebKit/Source/core/editing/spellcheck/IdleSpellCheckCallback.h

 // 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.
 
 #ifndef IdleSpellCheckCallback_h
 #define IdleSpellCheckCallback_h
 
 #include "core/dom/IdleRequestCallback.h"
+#include "core/dom/SynchronousMutationObserver.h"
 #include "platform/Timer.h"
 
 namespace blink {
 
 class LocalFrame;
 class SpellCheckRequester;
 
 // Main class for the implementation of idle time spell checker.
-class CORE_EXPORT IdleSpellCheckCallback final : public IdleRequestCallback {
+class CORE_EXPORT IdleSpellCheckCallback final
+    : public IdleRequestCallback,
+      public SynchronousMutationObserver {

[yosin_UTC9, 2017/02/25 02:22:57]

FYI: We may want to introduce |DocumentShutdownObserver|. I saw some speed
regression due by |SMO::didChangeChildren()| which is called by
ContainerNode::appendChild() and insertBefore() in micro benchmark tests.

Since, |IdleSpellCheckerCallback| don't observer DOM mutation, it is good
candidate of |DocumentShutdownObserver|.
Another client is |FrameSelection| once we make |Editor| to observe node removal
for closing typing command.

Anyway, let's see performance bot for results.

+  DISALLOW_COPY_AND_ASSIGN(IdleSpellCheckCallback);
+  USING_GARBAGE_COLLECTED_MIXIN(IdleSpellCheckCallback);
+
  public:
   static IdleSpellCheckCallback* create(LocalFrame&);
   ~IdleSpellCheckCallback() override;
 
+  enum class State {
+    kInactive,
+    kHotModeRequested,
+    kInHotModeInvocation,
+    kColdModeTimerStarted,
+    kColdModeRequested,
+    kInColdModeInvocation
+  };
+
+  State state() const { return m_state; }
+
   // Transit to HotModeRequested, if possible. Called by operations that need
   // spell checker to follow up.
-  // TODO(xiaochengh): Add proper call sites.
-  void setNeedsHotModeInvocation();
-
-  // Transit to ColdModeTimerStarted, if possible. Sets up a timer, and requests
-  // cold mode invocation if no critical operation occurs before timer firing.
-  // TODO(xiaochengh): Add proper call sites.
-  void setNeedsColdModeInvocation();
+  void setNeedsInvocation();
 
   // Cleans everything up and makes the callback inactive. Should be called when
   // document is detached or spellchecking is globally disabled.
-  // TODO(xiaochengh): Add proper call sites.
   void deactivate();
 
+  void documentAttached(Document*);
+
   // Exposed for testing only.
   SpellCheckRequester& spellCheckRequester() const;
+  void forceInvocationForTesting();
+  void setNeedsMoreColdModeInvocationForTesting() {
+    m_needsMoreColdModeInvocationForTesting = true;
+  }
+  void skipColdModeTimerForTesting();
+  int idleCallbackHandle() const { return m_idleCallbackHandle; }
 
   DECLARE_VIRTUAL_TRACE();
 
  private:
   explicit IdleSpellCheckCallback(LocalFrame&);
   void handleEvent(IdleDeadline*) override;
 
   LocalFrame& frame() const { return *m_frame; }
 
-  enum class State {
-    kInactive,
-    kHotModeRequested,
-    kInHotModeInvocation,
-    kColdModeTimerStarted,
-    kColdModeRequested,
-    kInColdModeInvocation
-  };
-
   // Returns whether spell checking is globally enabled.
   bool isSpellCheckingEnabled() const;
 
   // Calls requestIdleCallback with this IdleSpellCheckCallback.
   void requestInvocation();
 
   // Functions for hot mode.
   void hotModeInvocation(IdleDeadline*);
 
+  // Transit to ColdModeTimerStarted, if possible. Sets up a timer, and requests
+  // cold mode invocation if no critical operation occurs before timer firing.
+  void setNeedsColdModeInvocation();
+
   // Functions for cold mode.
   void coldModeTimerFired(TimerBase*);
   void coldModeInvocation(IdleDeadline*);
   bool coldModeFinishesFullDocument() const;
 
+  // Implements |SynchronousMutationObserver|.
+  void contextDestroyed(Document*) final;
+
   State m_state;
+  int m_idleCallbackHandle;
+  mutable bool m_needsMoreColdModeInvocationForTesting;
   const Member<LocalFrame> m_frame;
 
   TaskRunnerTimer<IdleSpellCheckCallback> m_coldModeTimer;
 };
 
 }  // namespace blink
 
 #endif  // IdleSpellCheckCallback_h