WIP: Plumbing input event latency reporting through Mus GPU.

content/browser/renderer_host/input/render_widget_host_latency_tracker.h

Index: content/browser/renderer_host/input/render_widget_host_latency_tracker.h
diff --git a/content/browser/renderer_host/input/render_widget_host_latency_tracker.h b/content/browser/renderer_host/input/render_widget_host_latency_tracker.h
index 520e7ee9d100287283a7d754e89a884ecadaa938..d1d607a1892ae87a0971282c555dbea7d4c1f18b 100644
--- a/content/browser/renderer_host/input/render_widget_host_latency_tracker.h
+++ b/content/browser/renderer_host/input/render_widget_host_latency_tracker.h
@@ -14,6 +14,7 @@
 #include "content/common/content_export.h"
 #include "content/common/input/input_event_ack_state.h"
 #include "ui/latency/latency_info.h"
+#include "ui/latency/latency_tracker.h"
 
 namespace content {
 
@@ -21,7 +22,8 @@ class RenderWidgetHostDelegate;
 
 // Utility class for tracking the latency of events passing through
 // a given RenderWidgetHost.
-class CONTENT_EXPORT RenderWidgetHostLatencyTracker {
+class CONTENT_EXPORT RenderWidgetHostLatencyTracker
+    : NON_EXPORTED_BASE(public ui::LatencyTracker) {
  public:
   explicit RenderWidgetHostLatencyTracker();
   ~RenderWidgetHostLatencyTracker();
@@ -54,11 +56,6 @@ class CONTENT_EXPORT RenderWidgetHostLatencyTracker {
   // update from the renderer.
   void OnSwapCompositorFrame(std::vector<ui::LatencyInfo>* latencies);
 
-  // Terminates latency tracking for events that triggered rendering, also
-  // performing relevant UMA latency reporting.
-  // Called when the RenderWidgetHost receives a swap update from the GPU.
-  void OnGpuSwapBuffersCompleted(const ui::LatencyInfo& latency);
-
   // WebInputEvent coordinates are in DPIs, while LatencyInfo expects
   // coordinates in device pixels.
   void set_device_scale_factor(float device_scale_factor) {
@@ -74,6 +71,12 @@ class CONTENT_EXPORT RenderWidgetHostLatencyTracker {
   void SetDelegate(RenderWidgetHostDelegate*);
 
  private:
+  // ui::LatencyTracker:
+  void ReportRapporScrollLatency(
+      const std::string& name,
+      const ui::LatencyInfo::LatencyComponent& start_component,
+      const ui::LatencyInfo::LatencyComponent& end_component) override;
+
   int64_t last_event_id_;
   int64_t latency_component_id_;
   float device_scale_factor_;