Bug 1307675 - Part 2: Record telemetry for time to first input. r=baku, data=bsmedberg

layout/base/nsPresContext.cpp

@@ -77,6 +77,7 @@
 #include "mozilla/StyleSheet.h"
 #include "mozilla/StyleSheetInlines.h"
 #include "mozilla/ServoRestyleManagerInlines.h"
+#include "mozilla/Telemetry.h"
 
 #if defined(MOZ_WIDGET_GTK)
 #include "gfxPlatformGtk.h" // xxx - for UseFcFontList
@@ -1617,6 +1618,15 @@ nsPresContext::RecordInteractionTime(InteractionType aType)
     &nsPresContext::mFirstScrollTime
   };
 
+  // Array of histogram IDs for the different interaction types,
+  // keyed by InteractionType.
+  Telemetry::ID histogramIds[] = {
+    Telemetry::TIME_TO_FIRST_CLICK,
+    Telemetry::TIME_TO_FIRST_KEY_INPUT,
+    Telemetry::TIME_TO_FIRST_MOUSE_MOVE,
+    Telemetry::TIME_TO_FIRST_SCROLL
+  };
+
   TimeStamp& interactionTime = this->*(
     interactionTimes[static_cast<uint32_t>(aType)]);
   if (!interactionTime.IsNull()) {
@@ -1647,7 +1657,11 @@ nsPresContext::RecordInteractionTime(InteractionType aType)
   // Only the top level content pres context reports first interaction
   // time to telemetry (if it hasn't already done so).
   if (this == topContentPresContext) {
-    // TODO: Record telemetry. See part 2 patch.
+    if (Telemetry::CanRecordExtended()) {
+       double millis = (interactionTime - mFirstPaintTime).ToMilliseconds();
+       Telemetry::Accumulate(histogramIds[static_cast<uint32_t>(aType)],
+                             millis);
+    }
   } else {
     topContentPresContext->RecordInteractionTime(aType);
   }

toolkit/components/telemetry/Histograms.json

@@ -10602,6 +10602,42 @@
     "n_values": 4,
     "description": "Counts the number of asm.js vs WebAssembly modules instanciations, at the time modules are getting instanciated."
   },
+  "TIME_TO_FIRST_CLICK": {
+    "alert_emails": ["hkirschner@mozilla.com"],
+    "bug_numbers": [1307675],
+    "expires_in_version": "58",
+    "kind": "exponential",
+    "high": 100000,
+    "n_buckets": 30,
+    "description": "Time in milliseconds from first paint to first click per top-level content browsing context."
+  },
+  "TIME_TO_FIRST_KEY_INPUT": {
+    "alert_emails": ["hkirschner@mozilla.com"],
+    "bug_numbers": [1307675],
+    "expires_in_version": "58",
+    "kind": "exponential",
+    "high": 100000,
+    "n_buckets": 30,
+    "description": "Time in milliseconds from first paint to first key input per top-level content browsing context."
+  },
+  "TIME_TO_FIRST_MOUSE_MOVE": {
+    "alert_emails": ["hkirschner@mozilla.com"],
+    "bug_numbers": [1307675],
+    "expires_in_version": "58",
+    "kind": "exponential",
+    "high": 100000,
+    "n_buckets": 30,
+    "description": "Time in milliseconds from first paint to first mouse move per top-level content browsing context."
+  },
+  "TIME_TO_FIRST_SCROLL": {
+    "alert_emails": ["hkirschner@mozilla.com"],
+    "bug_numbers": [1307675],
+    "expires_in_version": "58",
+    "kind": "exponential",
+    "high": 100000,
+    "n_buckets": 30,
+    "description": "Time in milliseconds from first paint to first scroll per top-level content browsing context."
+  },
   "DOCUMENT_WITH_EXPANDED_PRINCIPAL": {
     "alert_emails": ["dev-platform@lists.mozilla.org"],
     "bug_numbers": [1301123],