inspector: Replace Timer usages with TaskRunnerTimer in InspectorRevalidateDOMTask

This is part of efforts to replace default timer task runners with
other appropriate task runners in the renderer.

Bug: 624694, 804694
Change-Id: I0c9b53b15ddca0b65312f599f1cc83ace14f8b75
Reviewed-on: https://chromium-review.googlesource.com/896678Reviewed-by: Alexander Timin <altimin@chromium.org>
Reviewed-by: Andrey Kosyakov <caseq@chromium.org>
Reviewed-by: Alexei Filippov <alph@chromium.org>
Commit-Queue: Hajime Hoshi <hajimehoshi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#534671}

third_party/WebKit/Source/core/inspector/InspectorDOMAgent.cpp

@@ -83,6 +83,7 @@
 #include "platform/wtf/PtrUtil.h"
 #include "platform/wtf/text/CString.h"
 #include "platform/wtf/text/WTFString.h"
+#include "public/platform/TaskType.h"
 
 namespace blink {
 
@@ -112,14 +113,17 @@ class InspectorRevalidateDOMTask final
 
  private:
   Member<InspectorDOMAgent> dom_agent_;
-  Timer<InspectorRevalidateDOMTask> timer_;
+  TaskRunnerTimer<InspectorRevalidateDOMTask> timer_;
   HeapHashSet<Member<Element>> style_attr_invalidated_elements_;
 };
 
 InspectorRevalidateDOMTask::InspectorRevalidateDOMTask(
     InspectorDOMAgent* dom_agent)
     : dom_agent_(dom_agent),
-      timer_(this, &InspectorRevalidateDOMTask::OnTimer) {}
+      timer_(
+          dom_agent->GetDocument()->GetTaskRunner(TaskType::kDOMManipulation),
+          this,
+          &InspectorRevalidateDOMTask::OnTimer) {}
 
 void InspectorRevalidateDOMTask::ScheduleStyleAttrRevalidationFor(
     Element* element) {