Expand UMA coverage for compositor-handled events and fling FPS

content/renderer/input/input_handler_proxy.cc

Index: content/renderer/input/input_handler_proxy.cc
diff --git a/content/renderer/input/input_handler_proxy.cc b/content/renderer/input/input_handler_proxy.cc
index 0d4b17320a1986903d7c6942d404731474f9c534..6c4a9f29f8352748b16d20b70c6d748ac22e02aa 100644
--- a/content/renderer/input/input_handler_proxy.cc
+++ b/content/renderer/input/input_handler_proxy.cc
@@ -115,11 +115,15 @@ WebGestureEvent ObtainGestureScrollBegin(const WebGestureEvent& event) {
   return scroll_begin_event;
 }
 
-void SendScrollLatencyUma(const WebInputEvent& event,
-                          const ui::LatencyInfo& latency_info) {
+void ReportInputEventLatencyUma(const WebInputEvent& event,
+                                const ui::LatencyInfo& latency_info) {
   if (!(event.type == WebInputEvent::GestureScrollBegin ||
-        event.type == WebInputEvent::GestureScrollUpdate))
+        event.type == WebInputEvent::GestureScrollUpdate ||
+        event.type == WebInputEvent::GesturePinchBegin ||
+        event.type == WebInputEvent::GesturePinchUpdate ||
+        event.type == WebInputEvent::GestureFlingStart)) {
     return;
+  }
 
   ui::LatencyInfo::LatencyMap::const_iterator it =
       latency_info.latency_components.find(std::make_pair(
@@ -130,17 +134,42 @@ void SendScrollLatencyUma(const WebInputEvent& event,
 
   base::TimeDelta delta = base::TimeTicks::HighResNow() - it->second.event_time;
   for (size_t i = 0; i < it->second.event_count; ++i) {
-    UMA_HISTOGRAM_CUSTOM_COUNTS(
-        "Event.Latency.RendererImpl.GestureScroll2",
-        delta.InMicroseconds(),
-        1,
-        1000000,
-        100);
+    switch (event.type) {
+      case blink::WebInputEvent::GestureScrollBegin:
+        UMA_HISTOGRAM_CUSTOM_COUNTS(
+            "Event.Latency.RendererImpl.GestureScrollBegin",

[tdresser, 2014/12/02 14:42:27]

I think factoring out the histogram name here would improve readability.

+            delta.InMicroseconds(), 1, 1000000, 100);
+        break;
+      case blink::WebInputEvent::GestureScrollUpdate:
+        UMA_HISTOGRAM_CUSTOM_COUNTS(
+            // So named for historical reasons.
+            "Event.Latency.RendererImpl.GestureScroll2",
+            delta.InMicroseconds(), 1, 1000000, 100);
+        break;
+      case blink::WebInputEvent::GesturePinchBegin:
+        UMA_HISTOGRAM_CUSTOM_COUNTS(
+            "Event.Latency.RendererImpl.GesturePinchBegin",
+            delta.InMicroseconds(), 1, 1000000, 100);
+        break;
+      case blink::WebInputEvent::GesturePinchUpdate:
+        UMA_HISTOGRAM_CUSTOM_COUNTS(
+            "Event.Latency.RendererImpl.GesturePinchUpdate",
+            delta.InMicroseconds(), 1, 1000000, 100);
+        break;
+      case blink::WebInputEvent::GestureFlingStart:
+        UMA_HISTOGRAM_CUSTOM_COUNTS(
+            "Event.Latency.RendererImpl.GestureFlingStart",
+            delta.InMicroseconds(), 1, 1000000, 100);
+        break;
+      default:
+        NOTREACHED();
+        break;
+    }
   }
-}  // namespace
-
 }
 
+}  // namespace
+
 namespace content {
 
 InputHandlerProxy::InputHandlerProxy(cc::InputHandler* input_handler,
@@ -156,7 +185,9 @@ InputHandlerProxy::InputHandlerProxy(cc::InputHandler* input_handler,
       fling_may_be_active_on_main_thread_(false),
       disallow_horizontal_fling_scroll_(false),
       disallow_vertical_fling_scroll_(false),
-      has_fling_animation_started_(false) {
+      has_fling_animation_started_(false),
+      uma_latency_reporting_enabled_(
+          base::TimeTicks::IsHighResNowFastAndReliable()) {

[tdresser, 2014/12/02 14:42:27]

Do you know if other metrics report low res data, or if they suppress reporting
if high res data isn't available?

Not reporting anything is probably more correct. We should try to unify this at
some point.

[jdduke (slow), 2014/12/02 20:04:56]

Good question, I'd have to defer to Yufeng. What is curious is that the
histogram description for GestureScroll2 mentions
|IsHighResNowFastAndReliable()|, yet we weren't actually making that query
before when logging the metric. As long as we're consistent between main/impl
threads I don't have a strong preference.

[miletus1, 2014/12/02 22:22:34]

I don't remember GestureScroll2 is conditioned on
|IsHighResNowFastAndReliable()|. I think it might just a copy over from
Event.Latency.Renderer2 's description incorrectly.

   DCHECK(client);
   input_handler_->BindToClient(this);
   smooth_scroll_enabled_ = CommandLine::ForCurrentProcess()->HasSwitch(
@@ -185,7 +216,8 @@ InputHandlerProxy::HandleInputEventWithLatencyInfo(
     ui::LatencyInfo* latency_info) {
   DCHECK(input_handler_);
 
-  SendScrollLatencyUma(event, *latency_info);
+  if (uma_latency_reporting_enabled_)
+    ReportInputEvenLatencyUma(event, *latency_info);
 
   TRACE_EVENT_FLOW_STEP0("input",
                          "LatencyInfo.Flow",