Report user actions when gesture starts and stops in user_model.

content/renderer/render_thread_impl.cc

Index: content/renderer/render_thread_impl.cc
diff --git a/content/renderer/render_thread_impl.cc b/content/renderer/render_thread_impl.cc
index d3ee4b8dce527ffa822c17609e5400d8b4f9489a..1c00fa1780bd3c7c7daf109e72d6d4c4e3ff83f4 100644
--- a/content/renderer/render_thread_impl.cc
+++ b/content/renderer/render_thread_impl.cc
@@ -735,6 +735,12 @@ void RenderThreadImpl::Init(
 
   cc::SetClientNameForMetrics("Renderer");
 
+  if (!command_line.HasSwitch(switches::kSingleProcess)) {
+    action_callback_ = base::Bind(&RenderThreadImpl::RecordComputedAction,
+                                  base::Unretained(this));
+    base::AddActionCallback(action_callback_);
+  }
+
   is_threaded_animation_enabled_ =
       !command_line.HasSwitch(cc::switches::kDisableThreadedAnimation);
 
@@ -856,6 +862,9 @@ void RenderThreadImpl::Shutdown() {
   FOR_EACH_OBSERVER(
       RenderProcessObserver, observers_, OnRenderProcessShutdown());
 
+  if (!action_callback_.is_null())
+    base::RemoveActionCallback(action_callback_);
+
   if (memory_observer_) {
     message_loop()->RemoveTaskObserver(memory_observer_.get());
     memory_observer_.reset();