RequestIdleCallback: Avoid retaining ScriptedIdleTaskController while a cancelled timeout is pending

third_party/WebKit/Source/core/dom/ScriptedIdleTaskController.cpp

Index: third_party/WebKit/Source/core/dom/ScriptedIdleTaskController.cpp
diff --git a/third_party/WebKit/Source/core/dom/ScriptedIdleTaskController.cpp b/third_party/WebKit/Source/core/dom/ScriptedIdleTaskController.cpp
index b0bdb09aeb8c4f3fada72a03476c28700fc39e66..22736848645e1f01f47668e5c0e1b9df833b78be 100644
--- a/third_party/WebKit/Source/core/dom/ScriptedIdleTaskController.cpp
+++ b/third_party/WebKit/Source/core/dom/ScriptedIdleTaskController.cpp
@@ -34,12 +34,21 @@ public:
     static void idleTaskFired(PassRefPtr<IdleRequestCallbackWrapper> callbackWrapper, double deadlineSeconds)
     {
         // TODO(rmcilroy): Implement clamping of deadline in some form.
-        callbackWrapper->controller()->callbackFired(callbackWrapper->id(), deadlineSeconds, IdleDeadline::CallbackType::CalledWhenIdle);
+        if (RefPtrWillBeRawPtr<ScriptedIdleTaskController> controller = callbackWrapper->controller())
+            controller->callbackFired(callbackWrapper->id(), deadlineSeconds, IdleDeadline::CallbackType::CalledWhenIdle);
+        callbackWrapper->cancel();
     }
 
     static void timeoutFired(PassRefPtr<IdleRequestCallbackWrapper> callbackWrapper)
     {
-        callbackWrapper->controller()->callbackFired(callbackWrapper->id(), monotonicallyIncreasingTime(), IdleDeadline::CallbackType::CalledByTimeout);
+        if (RefPtrWillBeRawPtr<ScriptedIdleTaskController> controller = callbackWrapper->controller())
+            controller->callbackFired(callbackWrapper->id(), monotonicallyIncreasingTime(), IdleDeadline::CallbackType::CalledByTimeout);
+        callbackWrapper->cancel();
+    }
+
+    void cancel()
+    {
+        m_controller = nullptr;
     }
 
     ScriptedIdleTaskController::CallbackId id() const { return m_id; }