Hooks together Geolocation Feature in the Client and Engine.

blimp/engine/feature/geolocation/engine_geolocation_feature.cc

Index: blimp/engine/feature/geolocation/engine_geolocation_feature.cc
diff --git a/blimp/engine/feature/geolocation/engine_geolocation_feature.cc b/blimp/engine/feature/geolocation/engine_geolocation_feature.cc
index 4cce48905ee5dd38c999ad81fc49f970beb7e981..13eee8ba12e7f2d22bffa1a7d4903710089de0d3 100644
--- a/blimp/engine/feature/geolocation/engine_geolocation_feature.cc
+++ b/blimp/engine/feature/geolocation/engine_geolocation_feature.cc
@@ -9,6 +9,7 @@
 
 #include "base/memory/ptr_util.h"
 #include "base/memory/weak_ptr.h"
+#include "base/threading/thread_task_runner_handle.h"
 #include "blimp/common/create_blimp_message.h"
 #include "blimp/common/proto/blimp_message.pb.h"
 #include "blimp/common/proto/geolocation.pb.h"
@@ -20,6 +21,7 @@
 namespace blimp {
 namespace engine {
 namespace {
+
 class BlimpGeolocationDelegate : public device::GeolocationDelegate {
  public:
   explicit BlimpGeolocationDelegate(
@@ -120,7 +122,8 @@ void EngineGeolocationFeature::ProcessMessage(
 
 void EngineGeolocationFeature::NotifyCallback(
     const device::Geoposition& position) {
-  geoposition_received_callback_.Run(position);
+  task_runner_->PostTask(FROM_HERE,
+                         base::Bind(geoposition_received_callback_, position));
 }
 
 void EngineGeolocationFeature::RequestAccuracy(
@@ -151,6 +154,12 @@ void EngineGeolocationFeature::OnPermissionGranted() {
 void EngineGeolocationFeature::SetUpdateCallback(
     const GeopositionReceivedCallback& callback) {
   geoposition_received_callback_ = callback;
+  SetTaskRunner(base::ThreadTaskRunnerHandle::Get());

[Kevin M, 2016/09/01 20:01:07]

This probably doesn't need a helper function - maybe just split it into a
separate block w/a blank line and a little comment at the top.

[CJ, 2016/09/01 22:59:42]

Done.

+}
+
+void EngineGeolocationFeature::SetTaskRunner(

[Kevin M, 2016/09/01 20:01:07]

Recommend renaming |task_runner_| to |callback_task_runner_|, to make it crystal
clear which operations are being posted to the TaskRunner.

[CJ, 2016/09/01 22:59:42]

Done.

+    scoped_refptr<base::SingleThreadTaskRunner> runner) {
+  task_runner_ = std::move(runner);
 }
 
 }  // namespace engine