Introduce WebTaskRunner Patch 5/5

Remove obsolete WebThread::Task class.

Patch 1: https://codereview.chromium.org/1325073002
Patch 2: https://codereview.chromium.org/1308183005
Patch 3: https://codereview.chromium.org/1303153005
Patch 4: https://codereview.chromium.org/1309423004

BUG=510398, 497761

Review URL: https://codereview.chromium.org/1310253009

git-svn-id: svn://svn.chromium.org/blink/trunk@201812 bbb929c8-8fbe-4397-9dbb-9b2b20218538
diff --git a/third_party/WebKit/public/platform/WebThread.h b/third_party/WebKit/public/platform/WebThread.h
index 0a33dac..b84f76ff 100644
--- a/third_party/WebKit/public/platform/WebThread.h
+++ b/third_party/WebKit/public/platform/WebThread.h
@@ -50,13 +50,6 @@
         virtual void run(double deadlineSeconds) = 0;
     };
 
-    // TODO(alexclarke): Remove this once it's no longer referenced by chromium.
-    class BLINK_PLATFORM_EXPORT Task {
-    public:
-        virtual ~Task() { }
-        virtual void run() = 0;
-    };
-
     class BLINK_PLATFORM_EXPORT TaskObserver {
     public:
         virtual ~TaskObserver() { }
@@ -64,12 +57,6 @@
         virtual void didProcessTask() = 0;
     };
 
-    // postTask() and postDelayedTask() take ownership of the passed Task
-    // object. It is safe to invoke postTask() and postDelayedTask() from any
-    // thread.
-    // TODO(alexclarke): Remove postTask & postDelayedTask.
-    virtual void postTask(const WebTraceLocation&, Task*) { }
-    virtual void postDelayedTask(const WebTraceLocation&, Task*, long long delayMs) { };
 
     // Returns a WebTaskRunner bound to the underlying scheduler's default task queue.
     virtual WebTaskRunner* taskRunner() { return nullptr; }