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 a46a7edb2a42b765439f5b35c4a15a12e9239b67..a1770ede7cde6157b245b280ab4f360da6eeaac0 100644
--- a/content/renderer/render_thread_impl.cc
+++ b/content/renderer/render_thread_impl.cc
@@ -635,6 +635,11 @@ RenderThreadImpl::RenderThreadImpl(
 void RenderThreadImpl::Init() {
   TRACE_EVENT0("startup", "RenderThreadImpl::Init");
 
+  base::RemoveActionCallback(action_callback_);

[Sami, 2016/03/23 11:33:16]

AFAICT Init() will only ever be called once, so is it necessary to do this?

[beaudoin, 2016/03/23 18:43:22]

I don't know. I copied the pattern from metrics_service.cc. Since two ppl
commented on it, I'll remove it. :)

Done.

+  action_callback_ = base::Bind(&RenderThreadImpl::RecordComputedAction,
+                                base::Unretained(this));
+  base::AddActionCallback(action_callback_);
+
   base::trace_event::TraceLog::GetInstance()->SetThreadSortIndex(
       base::PlatformThread::CurrentId(),
       kTraceEventRendererMainThreadSortIndex);
@@ -852,6 +857,7 @@ void RenderThreadImpl::Init() {
 }
 
 RenderThreadImpl::~RenderThreadImpl() {
+  base::RemoveActionCallback(action_callback_);
 }
 
 void RenderThreadImpl::Shutdown() {