Add spec links and more descriptions of the different task types.

third_party/WebKit/Source/core/dom/TaskRunnerHelper.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 TaskRunnerHelper_h
 #define TaskRunnerHelper_h
 
 #include "core/CoreExport.h"
 #include "wtf/Allocator.h"
 #include "wtf/HashTraits.h"
 
 namespace blink {
 
 class Document;
 class ExecutionContext;
 class LocalFrame;
 class ScriptState;
 class WebTaskRunner;
 
 enum class TaskType : unsigned {
   // Speced tasks and related internal tasks should be posted to one of
   // the following task runners. These task runners may be throttled.
+
+  // https://html.spec.whatwg.org/multipage/webappapis.html#generic-task-sources
+  //
+  // This task source is used for features that react to DOM manipulations, such
+  // as things that happen in a non-blocking fashion when an element is inserted
+  // into the document.
   DOMManipulation,
+  // This task source is used for features that react to user interaction, for
+  // example keyboard or mouse input. Events sent in response to user input
+  // (e.g. click events) must be fired using tasks queued with the user
+  // interaction task source.
   UserInteraction,
+  // This task source is used for features that trigger in response to network
+  // activity.
   Networking,
+  // This task source is used to queue calls to history.back() and similar APIs.
   HistoryTraversal,
+
+  // https://html.spec.whatwg.org/multipage/embedded-content.html#the-embed-element
+  // This task source is used for the embed element setup steps.
   Embed,
+
+  // https://html.spec.whatwg.org/multipage/embedded-content.html#media-elements
+  // This task source is used for all tasks queued in the [Media elements]
+  // section and subsections of the spec unless explicitly specified otherwise.
   MediaElementEvent,
+
+  // https://html.spec.whatwg.org/multipage/scripting.html#the-canvas-element
+  // This task source is used to invoke the result callback of
+  // HTMLCanvasElement.toBlob().
   CanvasBlobSerialization,
+
+  // https://html.spec.whatwg.org/multipage/webappapis.html#event-loop-processing-model
+  // This task source is used when an algorithm requires a microtask to be
+  // queued.
   Microtask,
+
+  // https://html.spec.whatwg.org/multipage/webappapis.html#timers
+  // This task source is used to queue tasks queued by setInterval() and similar
+  // APIs.
   Timer,
+
+  // https://html.spec.whatwg.org/multipage/comms.html#sse-processing-model
+  // This task source is used for any tasks that are queued by EventSource
+  // objects.
   RemoteEvent,
+
+  // https://html.spec.whatwg.org/multipage/comms.html#feedback-from-the-protocol
+  // The task source for all tasks queued in the [WebSocket] section of the
+  // spec.
   WebSocket,
+
+  // https://html.spec.whatwg.org/multipage/comms.html#web-messaging
+  // This task source is used for the tasks in cross-document messaging.
   PostedMessage,
+
+  // https://html.spec.whatwg.org/multipage/comms.html#message-ports
   UnshippedPortMessage,
+
+  // https://www.w3.org/TR/FileAPI/#blobreader-task-source
+  // This task source is used for all tasks queued in the FileAPI spec to read
+  // byte sequences associated with Blob and File objects.
   FileReading,
+
+  // https://www.w3.org/TR/IndexedDB/#request-api
   DatabaseAccess,
+
+  // https://w3c.github.io/presentation-api/#common-idioms
+  // This task source is used for all tasks in the Presentation API spec.
   Presentation,
+
+  // https://www.w3.org/TR/2016/WD-generic-sensor-20160830/#sensor-task-source
+  // This task source is used for all tasks in the Sensor API spec.
   Sensor,
 
   // Use MiscPlatformAPI for a task that is defined in the spec but is not yet
   // associated with any specific task runner in the spec. MiscPlatformAPI is
   // not encouraged for stable and matured APIs. The spec should define the task
   // runner explicitly.
   // The task runner may be throttled.
   MiscPlatformAPI,
 
   // Other internal tasks that cannot fit any of the above task runners
@@ skipping 31 matching lines @@
  public:
   static RefPtr<WebTaskRunner> get(TaskType, LocalFrame*);
   static RefPtr<WebTaskRunner> get(TaskType, Document*);
   static RefPtr<WebTaskRunner> get(TaskType, ExecutionContext*);
   static RefPtr<WebTaskRunner> get(TaskType, ScriptState*);
 };
 
 }  // namespace blink
 
 #endif