RequestIdleCallback: Avoid retaining ScriptedIdleTaskController while a...

RequestIdleCallback: Avoid retaining ScriptedIdleTaskController while a cancelled timeout is pending

Ensure that ScriptedIdleTaskController does not get unnecessarily retained by a cancelled timeout task if the
idle task has been triggered, but the document has gone away.

BUG=595155

Committed: https://crrev.com/82f18cd2a7b718c4d5356222017d9855a53eb6f3
Cr-Commit-Position: refs/heads/master@{#381489}

Review URL: https://codereview.chromium.org/1808643003

Cr-Commit-Position: refs/heads/master@{#381710}

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; }