Bug 1518717 - Update webrender to commit ff9940fdf95412a3e5d1a70c78defba6e919c170 (WR PR #3488). r=kats

https://github.com/servo/webrender/pull/3488

Differential Revision: https://phabricator.services.mozilla.com/D16039

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

gfx/webrender_bindings/revision.txt

@@ -1 +1 @@
-fb4b9342aa1b047ac46b89cb7a70987816bee686
+ff9940fdf95412a3e5d1a70c78defba6e919c170

gfx/wr/webrender/src/freelist.rs

@@ -263,6 +263,7 @@ impl<T, M> FreeList<T, M> {
         slot.value.take().unwrap()
     }
 
+    #[allow(dead_code)]
     pub fn len(&self) -> usize {
         self.active_count
     }

gfx/wr/webrender/src/texture_cache.rs

@@ -526,7 +526,8 @@ impl TextureCache {
         self.debug_flags = flags;
     }
 
-    pub fn clear(&mut self) {
+    /// Clear all standalone textures in the cache.
+    pub fn clear_standalone(&mut self) {
         let standalone_entry_handles = mem::replace(
             &mut self.handles.standalone,
             Vec::new(),
@@ -537,7 +538,10 @@ impl TextureCache {
             entry.evict();
             self.free(entry);
         }
+    }
 
+    /// Clear all shared textures in the cache.
+    pub fn clear_shared(&mut self) {
         let shared_entry_handles = mem::replace(
             &mut self.handles.shared,
             Vec::new(),
@@ -549,11 +553,16 @@ impl TextureCache {
             self.free(entry);
         }
 
-        assert!(self.entries.len() == 0);
-
         self.shared_textures.clear(&mut self.pending_updates);
     }
 
+    /// Clear all entries in the texture cache. This is a fairly drastic
+    /// step that should only be called very rarely.
+    pub fn clear(&mut self) {
+        self.clear_standalone();
+        self.clear_shared();
+    }
+
     /// Called at the beginning of each frame.
     pub fn begin_frame(&mut self, stamp: FrameStamp) {
         self.now = stamp;
@@ -597,7 +606,7 @@ impl TextureCache {
         if let Some(t) = self.reached_reclaim_threshold {
             let dur = self.now.time().duration_since(t).unwrap_or(Duration::default());
             if dur >= Duration::from_secs(5) {
-                self.clear();
+                self.clear_shared();
                 self.reached_reclaim_threshold = None;
             }
         }