Clean compositing inputs for location APIs for sticky-affected elements.

third_party/WebKit/Source/core/dom/DocumentTest.cpp

 /*
  * Copyright (c) 2014, 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 779 matching lines @@
       GetDocument().Loader()->GetApplicationCacheHost();
   appcache_host->host_ = WTF::MakeUnique<MockWebApplicationCacheHost>();
   appcache_host->SelectCacheWithManifest(
       KURL(KURL(), "https://test.com/foobar/manifest"));
   MockWebApplicationCacheHost* mock_web_host =
       static_cast<MockWebApplicationCacheHost*>(appcache_host->host_.get());
   EXPECT_FALSE(mock_web_host->with_manifest_was_called_);
   EXPECT_TRUE(mock_web_host->without_manifest_was_called_);
 }
 
+// Verifies that calling EnsurePaintLocationDataValidForNode cleans compositor
+// inputs only when necessary. We generally want to avoid cleaning the inputs,
+// as it is more expensive than just doing layout.
+TEST_F(DocumentTest,
+       EnsurePaintLocationDataValidForNodeCompositingInputsOnlyWhenNecessary) {
+  GetDocument().body()->setInnerHTML(
+      "<div id='ancestor'>"
+      "  <div id='sticky' style='position:sticky;'>"
+      "    <div id='stickyChild'></div>"
+      "  </div>"
+      "  <div id='nonSticky'></div>"
+      "</div>");
+  EXPECT_EQ(DocumentLifecycle::kStyleClean,
+            GetDocument().Lifecycle().GetState());
+
+  // Asking for any element that is not affected by a sticky element should only
+  // advance the lifecycle to layout clean.
+  GetDocument().EnsurePaintLocationDataValidForNode(
+      GetDocument().getElementById("ancestor"));
+  EXPECT_EQ(DocumentLifecycle::kLayoutClean,
+            GetDocument().Lifecycle().GetState());
+
+  GetDocument().EnsurePaintLocationDataValidForNode(
+      GetDocument().getElementById("nonSticky"));
+  EXPECT_EQ(DocumentLifecycle::kLayoutClean,
+            GetDocument().Lifecycle().GetState());
+
+  // However, asking for either the sticky element or it's descendents should
+  // clean compositing inputs as well.
+  GetDocument().EnsurePaintLocationDataValidForNode(
+      GetDocument().getElementById("sticky"));
+  EXPECT_EQ(DocumentLifecycle::kCompositingInputsClean,
+            GetDocument().Lifecycle().GetState());
+
+  // Dirty layout.
+  GetDocument().body()->setAttribute("style", "background: red;");
+  EXPECT_EQ(DocumentLifecycle::kVisualUpdatePending,
+            GetDocument().Lifecycle().GetState());
+
+  GetDocument().EnsurePaintLocationDataValidForNode(
+      GetDocument().getElementById("stickyChild"));
+  EXPECT_EQ(DocumentLifecycle::kCompositingInputsClean,
+            GetDocument().Lifecycle().GetState());
+}
+
 }  // namespace blink