Add input coordinate information to InputLatency

ui/events/latency_info.h

Index: ui/events/latency_info.h
diff --git a/ui/events/latency_info.h b/ui/events/latency_info.h
index 92d928d615837d1323f07112b9244c135af4e67d..40e9fa082ac6c3de6d84c153ab08a21b77798600 100644
--- a/ui/events/latency_info.h
+++ b/ui/events/latency_info.h
@@ -98,6 +98,11 @@ struct EVENTS_BASE_EXPORT LatencyInfo {
   // Empirically determined constant based on a typical scroll sequence.
   enum { kTypicalMaxComponentsPerLatencyInfo = 6 };
 
+  enum { kMaxInputCoordinates = 2 };
+  enum { kCoordinateDimensions = 2 };
+

[jdduke (slow), 2014/09/17 17:43:34]

If we can't use gfx::PointF, would this benefit from

struct LatencyCoordinate {
  LatencyCoordinate();
  float x, y;
};

?

[Sami, 2014/09/18 14:52:37]

Yes, that brings some well needed structure.

+  typedef float InputCoordinates[kMaxInputCoordinates][kCoordinateDimensions];
+
   // Map a Latency Component (with a component-specific int64 id) to a
   // component info.
   typedef base::SmallMap<
@@ -153,6 +158,11 @@ struct EVENTS_BASE_EXPORT LatencyInfo {
   void TraceEventType(const char* event_type);
 
   LatencyMap latency_components;

[jdduke (slow), 2014/09/17 17:43:34]

Are all these members public to simplify serialization? Seems rather unfortunate
:(

[Sami, 2014/09/18 14:52:37]

I guess that is the reason. Everything else mostly uses methods to access the
same data.

+
+  // These coordinates represent window coordinates of the original input event.
+  size_t input_coordinates_size;
+  InputCoordinates input_coordinates;
+
   // The unique id for matching the ASYNC_BEGIN/END trace event.
   int64 trace_id;
   // Whether a terminal component has been added.