Break down end-to-end scroll update latency UMA metrics

content/browser/renderer_host/render_widget_host_latency_tracker.cc

Index: content/browser/renderer_host/render_widget_host_latency_tracker.cc
diff --git a/content/browser/renderer_host/render_widget_host_latency_tracker.cc b/content/browser/renderer_host/render_widget_host_latency_tracker.cc
index 2d738c491910c4d429709da26d4ecd6193f9105b..3c3f92831fc6309d108ec07bcb80d2cfb9d9096b 100644
--- a/content/browser/renderer_host/render_widget_host_latency_tracker.cc
+++ b/content/browser/renderer_host/render_widget_host_latency_tracker.cc
@@ -171,6 +171,97 @@ void ComputeScrollLatencyHistograms(
             .InMicroseconds(),
         1, 1000000, 100);
   }
+
+  typedef std::pair<LatencyInfo::LatencyComponent, bool> ComponentPair;
+
+  ComponentPair rendering_scheduled_main_component;
+  ComponentPair rendering_scheduled_impl_component;
+  ComponentPair renderer_swap_component;

[jdduke (slow), 2015/02/11 23:22:02]

Do these always go together? If not, can we early out? If so, should we be
validating that?

[Yufeng Shen (Slow to review), 2015/02/12 02:59:02]

CHECK seems too restrict here. I will just do early return.

+  ComponentPair browser_received_swap_component;
+  ComponentPair gpu_swap_component;
+
+  rendering_scheduled_main_component.second =
+      latency.FindLatency(
+          ui::INPUT_EVENT_LATENCY_RENDERING_SCHEDULED_MAIN_COMPONENT,
+          0, &(rendering_scheduled_main_component.first));
+
+  rendering_scheduled_impl_component.second =
+      latency.FindLatency(
+          ui::INPUT_EVENT_LATENCY_RENDERING_SCHEDULED_IMPL_COMPONENT,
+          0, &(rendering_scheduled_impl_component.first));
+
+  renderer_swap_component.second =
+      latency.FindLatency(ui::INPUT_EVENT_LATENCY_RENDERER_SWAP_COMPONENT,
+                          0, &(renderer_swap_component.first));
+
+  browser_received_swap_component.second =
+      latency.FindLatency(
+          ui::INPUT_EVENT_BROWSER_RECEIVED_RENDERER_SWAP_COMPONENT,
+          0, &(browser_received_swap_component.first));
+
+  gpu_swap_component.second =
+      latency.FindLatency(ui::INPUT_EVENT_GPU_SWAP_BUFFER_COMPONENT,
+                          0, &(gpu_swap_component.first));
+
+  if (rendering_scheduled_main_component.second) {
+      UMA_HISTOGRAM_CUSTOM_COUNTS(
+          "Event.Latency.ScrollUpdateTouchToHandledMain",
+          (rendering_scheduled_main_component.first.event_time -
+           original_component.event_time).InMicroseconds(),
+          1, 1000000, 100);
+  }
+
+  if (rendering_scheduled_impl_component.second) {
+      UMA_HISTOGRAM_CUSTOM_COUNTS(
+          "Event.Latency.ScrollUpdateTouchToHandledImpl",
+          (rendering_scheduled_impl_component.first.event_time -
+           original_component.event_time).InMicroseconds(),
+          1, 1000000, 100);
+  }
+
+  if (renderer_swap_component.second) {
+    if (rendering_scheduled_main_component.second) {
+      UMA_HISTOGRAM_CUSTOM_COUNTS(
+          "Event.Latency.ScrollUpdateHandledMainToRendererSwap",
+          (renderer_swap_component.first.event_time -
+           rendering_scheduled_main_component.first.event_time).
+          InMicroseconds(),
+          1, 1000000, 100);
+    }
+
+    if (rendering_scheduled_impl_component.second) {
+      UMA_HISTOGRAM_CUSTOM_COUNTS(
+          "Event.Latency.ScrollUpdateHandledImplToRendererSwap",
+          (renderer_swap_component.first.event_time -
+           rendering_scheduled_impl_component.first.event_time).
+          InMicroseconds(),
+          1, 1000000, 100);
+    }
+
+    if (browser_received_swap_component.second) {
+      UMA_HISTOGRAM_CUSTOM_COUNTS(
+          "Event.Latency.ScrollUpdateRendererSwapToBrowserNotified",
+          (browser_received_swap_component.first.event_time -
+           renderer_swap_component.first.event_time).InMicroseconds(),
+          1, 1000000, 100);
+    }
+  }
+
+  if (gpu_swap_component.second) {
+    if (browser_received_swap_component.second) {
+      UMA_HISTOGRAM_CUSTOM_COUNTS(
+          "Event.Latency.ScrollUpdateBrowserNotifiedToBeforeGpuSwap",
+          (gpu_swap_component.first.event_time -
+           browser_received_swap_component.first.event_time).InMicroseconds(),
+          1, 1000000, 100);
+    }
+
+    UMA_HISTOGRAM_CUSTOM_COUNTS(
+        "Event.Latency.ScrollUpdateGpuSwap",
+        (swap_component.event_time -
+         gpu_swap_component.first.event_time).InMicroseconds(),
+        1, 1000000, 100);
+  }
 }
 
 // LatencyComponents generated in the renderer must have component IDs
@@ -264,7 +355,9 @@ void RenderWidgetHostLatencyTracker::OnInputEventAck(
 
   // Latency ends when it is acked but does not cause render scheduling.
   bool rendering_scheduled = latency->FindLatency(
-      ui::INPUT_EVENT_LATENCY_RENDERING_SCHEDULED_COMPONENT, 0, NULL);
+      ui::INPUT_EVENT_LATENCY_RENDERING_SCHEDULED_MAIN_COMPONENT, 0, nullptr);
+  rendering_scheduled |= latency->FindLatency(
+      ui::INPUT_EVENT_LATENCY_RENDERING_SCHEDULED_IMPL_COMPONENT, 0, nullptr);
 
   if (WebInputEvent::isGestureEventType(event.type)) {
     if (!rendering_scheduled) {