Do not call MemoryCache::prune() when a client/observer is removed

third_party/WebKit/Source/core/fetch/MemoryCacheTest.cpp

 /*
  * Copyright (c) 2013, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 294 matching lines @@
     memoryCache()->add(resource1);
     memoryCache()->add(resource2);
     // Call prune. There is nothing to prune, but this will initialize
     // the prune timestamp, allowing future prunes to be deferred.
     memoryCache()->prune();
     EXPECT_GT(resource1->decodedSize(), 0u);
     EXPECT_GT(resource2->decodedSize(), 0u);
     EXPECT_EQ(0u, memoryCache()->deadSize());
     EXPECT_EQ(resource1->size() + resource2->size(), memoryCache()->liveSize());
 
-    // Removing the client from resource1 should result in all resources
-    // remaining in cache since the prune is deferred.
+    // Removing the client from resource1 should not trigger pruning.
     client1->removeAsClient();
     EXPECT_GT(resource1->decodedSize(), 0u);
     EXPECT_GT(resource2->decodedSize(), 0u);
     EXPECT_EQ(resource1->size(), memoryCache()->deadSize());
     EXPECT_EQ(resource2->size(), memoryCache()->liveSize());
     EXPECT_TRUE(memoryCache()->contains(resource1));
     EXPECT_TRUE(memoryCache()->contains(resource2));
 
-    // Removing the client from resource2 should result in immediate
-    // eviction of resource2 because we are over the prune deferral limit.
+    // Removing the client from resource2 should not trigger pruning.
     client2->removeAsClient();
     EXPECT_GT(resource1->decodedSize(), 0u);
     EXPECT_GT(resource2->decodedSize(), 0u);
-    EXPECT_EQ(resource1->size(), memoryCache()->deadSize());
+    EXPECT_EQ(resource1->size() + resource2->size(), memoryCache()->deadSize());
     EXPECT_EQ(0u, memoryCache()->liveSize());
     EXPECT_TRUE(memoryCache()->contains(resource1));
-    EXPECT_FALSE(memoryCache()->contains(resource2));
+    EXPECT_TRUE(memoryCache()->contains(resource2));
+
+    WeakPersistent<Resource> resource1Weak = resource1;
+    WeakPersistent<Resource> resource2Weak = resource2;
+
+    ThreadState::current()->collectGarbage(BlinkGC::NoHeapPointersOnStack, BlinkGC::GCWithSweep, BlinkGC::ForcedGC);
+    // Resources are garbage-collected (WeakMemoryCache) and thus removed
+    // from MemoryCache.
+    EXPECT_FALSE(resource1Weak);
+    EXPECT_FALSE(resource2Weak);
+    EXPECT_EQ(0u, memoryCache()->deadSize());
+    EXPECT_EQ(0u, memoryCache()->liveSize());
 }
 
 TEST_F(MemoryCacheTest, ClientRemoval_Basic)
 {
     Resource* resource1 =
         FakeDecodedResource::create(ResourceRequest("http://foo.com"), Resource::Raw);
     Resource* resource2 =
         FakeDecodedResource::create(ResourceRequest("http://test/resource"), Resource::Raw);
     TestClientRemoval(resource1, resource2);
 }
@@ skipping 126 matching lines @@
     const KURL url2 = KURL(ParsedURLString, "http://test/resource2#foo");
     FakeResource* resource2 = FakeResource::create(ResourceRequest(url2), Resource::Raw);
     memoryCache()->add(resource2);
     EXPECT_TRUE(memoryCache()->contains(resource2));
 
     memoryCache()->removeURLFromCache(url2);
     EXPECT_FALSE(memoryCache()->contains(resource2));
 }
 
 } // namespace blink