Bug 1600793 - Make the scrolling input telemetry work for WebRender r…

…=botond,jrmuizel

Differential Revision: https://phabricator.services.mozilla.com/D60046

[ghsync] From https://hg.mozilla.org/mozilla-central/rev/85ffb23020709fdacd0f0b8e2d428178d5d56ef5

webrender/src/lib.rs

@@ -217,6 +217,7 @@ pub use crate::renderer::{
     RendererStats, SceneBuilderHooks, ThreadListener, ShaderPrecacheFlags,
     MAX_VERTEX_TEXTURE_WIDTH,
 };
+pub use crate::internal_types::FastHashMap;
 pub use crate::screen_capture::{AsyncScreenshotHandle, RecordedFrameHandle};
 pub use crate::shade::{Shaders, WrShaders};
 pub use api as webrender_api;

webrender/src/render_backend.rs

@@ -1481,19 +1481,20 @@ impl RenderBackend {
     ) {
         let requested_frame = render_frame;
 
+        let requires_frame_build = self.requires_frame_build();
+        let doc = self.documents.get_mut(&document_id).unwrap();
         // If we have a sampler, get more frame ops from it and add them
         // to the transaction. This is a hook to allow the WR user code to
         // fiddle with things after a potentially long scene build, but just
         // before rendering. This is useful for rendering with the latest
         // async transforms.
         if requested_frame || has_built_scene {
             if let Some(ref sampler) = self.sampler {
-                frame_ops.append(&mut sampler.sample(document_id));
+                frame_ops.append(&mut sampler.sample(document_id,
+                                                     &doc.scene.pipeline_epochs));
             }
         }
 
-        let requires_frame_build = self.requires_frame_build();
-        let doc = self.documents.get_mut(&document_id).unwrap();
         doc.has_built_scene |= has_built_scene;
 
         // If there are any additions or removals of clip modes

webrender/src/renderer.rs

@@ -6186,7 +6186,8 @@ pub trait AsyncPropertySampler {
     /// This is called for each transaction with the generate_frame flag set
     /// (i.e. that will trigger a render). The list of frame messages returned
     /// are processed as though they were part of the original transaction.
-    fn sample(&self, document_id: DocumentId) -> Vec<FrameMsg>;
+    fn sample(&self, document_id: DocumentId,
+              doc: &FastHashMap<PipelineId, Epoch>) -> Vec<FrameMsg>;
     /// This is called exactly once, when the render backend thread is about to
     /// terminate.
     fn deregister(&self);