Bug 1060200 (Part 2) - Add SurfaceCache::RemoveIfPresent so invalid entries can be freed eagerly. r=dholbert

image/src/SurfaceCache.cpp

@@ -339,6 +339,20 @@ public:
     return ref;
   }
 
+  void RemoveIfPresent(const ImageKey    aImageKey,
+                       const SurfaceKey& aSurfaceKey)
+  {
+    nsRefPtr<ImageSurfaceCache> cache = GetImageCache(aImageKey);
+    if (!cache)
+      return;  // No cached surfaces for this image.
+
+    nsRefPtr<CachedSurface> surface = cache->Lookup(aSurfaceKey);
+    if (!surface)
+      return;  // Lookup in the per-image cache missed.
+
+    Remove(surface);
+  }
+
   bool CanHold(const Cost aCost) const
   {
     return aCost <= mMaxCost;
@@ -537,6 +551,16 @@ SurfaceCache::CanHold(const IntSize& aSize)
   return sInstance->CanHold(cost);
 }
 
+/* static */ void
+SurfaceCache::RemoveIfPresent(const ImageKey    aImageKey,
+                              const SurfaceKey& aSurfaceKey)
+{
+  MOZ_ASSERT(sInstance, "Should be initialized");
+  MOZ_ASSERT(NS_IsMainThread());
+
+  return sInstance->RemoveIfPresent(aImageKey, aSurfaceKey);
+}
+
 /* static */ void
 SurfaceCache::Discard(Image* aImageKey)
 {

image/src/SurfaceCache.h

@@ -183,6 +183,18 @@ struct SurfaceCache
    */
   static bool CanHold(const IntSize& aSize);
 
+  /*
+   * Removes a surface from the cache, if it's present.
+   *
+   * Use this function to remove individual surfaces that have become invalid.
+   * Prefer Discard() or DiscardAll() when they're applicable, as they have much
+   * better performance than calling this function repeatedly.
+   *
+   * @param aImageKey    Key data identifying which image the surface belongs to.
+   * @param aSurfaceKey  Key data which uniquely identifies the requested surface.
+   */
+  static void RemoveIfPresent(const ImageKey    aImageKey,
+                              const SurfaceKey& aSurfaceKey);
   /*
    * Evicts any cached surfaces associated with the given image from the cache.
    * This MUST be called, at a minimum, when the image is destroyed. If