Add fd event support to EventTaskRunner

This change allows applications to perform
general I/O completion handling as part of the
Run() loop, rather than just timeout completion.

Change-Id: Idce97a33f7a35348ac5a7d226491f9907edc3405
Reviewed-on: https://weave-review.googlesource.com/1447
Reviewed-by: Vitaly Buka <vitalybuka@google.com>
diff --git a/examples/provider/event_http_client.h b/examples/provider/event_http_client.h
index 7ad117e..378c4a3 100644
--- a/examples/provider/event_http_client.h
+++ b/examples/provider/event_http_client.h
@@ -10,11 +10,11 @@
 #include <base/memory/weak_ptr.h>
 #include <weave/provider/http_client.h>
 
+#include "examples/provider/event_task_runner.h"
+
 namespace weave {
 namespace examples {
 
-class EventTaskRunner;
-
 // Basic implementation of weave::HttpClient using libevent.
 class EventHttpClient : public provider::HttpClient {
  public: