Bug 1580129 - Add COMPOSITE_TIME metric for geckoview_streaming telemetry. r=Dexter,chutten

Differential Revision: https://phabricator.services.mozilla.com/D46920

--HG--
extra : moz-landing-system : lando

toolkit/components/telemetry/Histograms.json

@@ -319,15 +319,15 @@
   },
   "COMPOSITE_TIME" : {
     "record_in_processes": ["main", "content", "gpu"],
-    "products": ["firefox", "fennec", "geckoview"],
-    "alert_emails": ["gfx-telemetry-alerts@mozilla.com", "rhunt@mozilla.com"],
+    "products": ["firefox", "fennec", "geckoview", "geckoview_streaming"],
+    "alert_emails": ["gfx-telemetry-alerts@mozilla.com", "jnicol@mozilla.com"],
     "expires_in_version": "never",
     "description": "Composite times in milliseconds",
     "kind": "exponential",
     "high": 1000,
     "n_buckets": 50,
     "releaseChannelCollection": "opt-out",
-    "bug_numbers": [1080160, 1529352]
+    "bug_numbers": [1080160, 1529352, 1580129]
   },
   "COMPOSITE_FRAME_ROUNDTRIP_TIME" : {
     "record_in_processes": ["main", "content", "gpu"],

toolkit/components/telemetry/geckoview/streaming/metrics.yaml

@@ -7,3 +7,23 @@
 # `glean_parser` PyPI package.
 
 $schema: moz://mozilla.org/schemas/glean/metrics/1-0-0
+
+gfx:
+  composite_time:
+    type: timing_distribution
+    time_unit: millisecond
+    gecko_datapoint: COMPOSITE_TIME
+    description: |
+      The time taken to composite a frame.
+      On non-webrender this is the time taken in `CompositorBridgeParent::CompositeToTarget()`.
+      On webrender, this is the time taken from the start of `WebRenderBridgeParent::CompositeToTarget()`, until the render thread has rendered the frame (in `RenderThread::HandleFrameOneDoc()`).
+    bugs:
+      - 1080160
+      - 1529352
+      - 1580129
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1580129#c7
+    notification_emails:
+      - gfx-telemetry-alerts@mozilla.com
+      - jnicol@mozilla.com
+    expires: never