Replace TaskType::kUnspecedTimer with kInternalIPC where IPC is related

We plan to eliminate kUnthrottled, kUnspecedTimer and kUnspecedLoading
and replace them with appropriate kInternal* task types.

Bug: 830489
Change-Id: If0f260c6c7d4ec9f8ca476bc6731e54f1d7cb7d2
Reviewed-on: https://chromium-review.googlesource.com/1005642Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Ken Rockot <rockot@chromium.org>
Commit-Queue: Hajime Hoshi <hajimehoshi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#550093}

third_party/blink/renderer/core/mojo/mojo_watcher.cc

@@ -72,7 +72,7 @@ void MojoWatcher::ContextDestroyed(ExecutionContext*) {
 MojoWatcher::MojoWatcher(ExecutionContext* context,
                          V8MojoWatchCallback* callback)
     : ContextLifecycleObserver(context),
-      task_runner_(context->GetTaskRunner(TaskType::kUnspecedTimer)),
+      task_runner_(context->GetTaskRunner(TaskType::kInternalIPC)),
       callback_(callback) {}
 
 MojoResult MojoWatcher::Watch(mojo::Handle handle,