Add Keyboard Latency UMA Metrics.

content/public/browser/render_widget_host.h

Index: content/public/browser/render_widget_host.h
diff --git a/content/public/browser/render_widget_host.h b/content/public/browser/render_widget_host.h
index 2ae1a08e1b52b0d6116fd7d3c4a1d815c5c17ddd..063c0272e4a9b63792400020bcda875206e35bcc 100644
--- a/content/public/browser/render_widget_host.h
+++ b/content/public/browser/render_widget_host.h
@@ -17,6 +17,7 @@
 #include "third_party/WebKit/public/platform/WebGestureEvent.h"
 #include "third_party/WebKit/public/platform/WebInputEvent.h"
 #include "third_party/WebKit/public/web/WebTextDirection.h"
+#include "ui/events/latency_info.h"

[mfomitchev, 2017/04/04 14:59:06]

Declare instead of including in .h.

[tdresser, 2017/05/01 15:49:21]

Done.

 #include "ui/gfx/geometry/size.h"
 #include "ui/surface/transport_dib.h"
 
@@ -163,8 +164,9 @@ class CONTENT_EXPORT RenderWidgetHost : public IPC::Sender {
       const blink::WebMouseEvent& mouse_event) = 0;
   virtual void ForwardWheelEvent(
       const blink::WebMouseWheelEvent& wheel_event) = 0;
-  virtual void ForwardKeyboardEvent(
-      const NativeWebKeyboardEvent& key_event) = 0;
+  virtual void ForwardKeyboardEventWithLatencyInfo(

[mfomitchev, 2017/04/04 14:59:06]

With other events we only have "WithLatencyInfo" variants in RWHImpl. Is there a
reason to break the pattern for key events? This also means we have to create
dummy LatencyInfo objects in a bunch of places instead of in once common place. 

[tdresser, 2017/05/01 15:49:21]

This is only required for FindBarHost, which has a native key event (with
LatencyInfo), and then wants to forward the event via the RWH.

We could have both methods here?

[mfomitchev, 2017/05/04 20:36:05]

Could FindBarHost do  RenderWidgetHostImpl::From()? Either way, I think it would
make sense to keep ForwardKeyboardEvent here, and have it create the LatencyInfo
object and call ForwardKeyboardEventWithLatencyInfo similar to other
ForwardXYZEvent variants. 

We are creating LatencyInfo for this method in vr_input_manager.cc,
autofill_interactive_uitest.cc, password_generation_interactive_uitest.cc,
input_handler.cc, render_widget_host_view_guest.cc,
render_widget_host_unittest.cc, render_widget_host_view_android.cc, etc. So
there's quite a bit of duplication which would be nice to get rid of.

[tdresser, 2017/05/09 15:29:25]

FindBarHost can't access RenderWidgetHostImpl due to DEPS, which I think are
probably correct.

I could add both methods to RWH?

[mfomitchev, 2017/05/09 17:35:23]

I see. That sounds reasonable to me - at least we'll get rid of the code
duplication.

[tdresser, 2017/05/10 14:27:15]

Done.

+      const NativeWebKeyboardEvent& key_event,
+      const ui::LatencyInfo& latency) = 0;
   virtual void ForwardGestureEvent(
       const blink::WebGestureEvent& gesture_event) = 0;