Avoid unnecessary updateActiveStyle comparing shadow styles.

third_party/WebKit/Source/core/css/resolver/ScopedStyleResolverTest.cpp

Index: third_party/WebKit/Source/core/css/resolver/ScopedStyleResolverTest.cpp
diff --git a/third_party/WebKit/Source/core/css/resolver/ScopedStyleResolverTest.cpp b/third_party/WebKit/Source/core/css/resolver/ScopedStyleResolverTest.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..689e4b45e34433bad1104b20cbbf8dd9c4727deb
--- /dev/null
+++ b/third_party/WebKit/Source/core/css/resolver/ScopedStyleResolverTest.cpp
@@ -0,0 +1,103 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "core/css/resolver/ScopedStyleResolver.h"
+
+#include "core/dom/shadow/ShadowRoot.h"
+#include "core/dom/shadow/ShadowRootInit.h"
+#include "core/frame/FrameView.h"
+#include "core/html/HTMLElement.h"
+#include "core/testing/DummyPageHolder.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace blink {
+
+class ScopedStyleResolverTest : public ::testing::Test {
+ protected:
+  void SetUp() override {
+    m_dummyPageHolder = DummyPageHolder::create(IntSize(800, 600));
+  }
+
+  Document& document() { return m_dummyPageHolder->document(); }
+  StyleEngine& styleEngine() { return document().styleEngine(); }
+  ShadowRoot& attachShadow(Element& host);
+
+ private:
+  std::unique_ptr<DummyPageHolder> m_dummyPageHolder;
+};
+
+ShadowRoot& ScopedStyleResolverTest::attachShadow(Element& host) {
+  ShadowRootInit init;
+  init.setMode("open");
+  ShadowRoot* shadowRoot = host.attachShadow(
+      ScriptState::forMainWorld(document().frame()), init, ASSERT_NO_EXCEPTION);
+  EXPECT_TRUE(shadowRoot);
+  return *shadowRoot;
+}
+
+TEST_F(ScopedStyleResolverTest, HasSameStylesNullNull) {
+  EXPECT_TRUE(ScopedStyleResolver::haveSameStyles(nullptr, nullptr));
+}
+
+TEST_F(ScopedStyleResolverTest, HasSameStylesNullEmpty) {
+  ScopedStyleResolver& resolver = document().ensureScopedStyleResolver();
+  EXPECT_TRUE(ScopedStyleResolver::haveSameStyles(nullptr, &resolver));
+  EXPECT_TRUE(ScopedStyleResolver::haveSameStyles(&resolver, nullptr));
+}
+
+TEST_F(ScopedStyleResolverTest, HasSameStylesEmptyEmpty) {
+  ScopedStyleResolver& resolver = document().ensureScopedStyleResolver();
+  EXPECT_TRUE(ScopedStyleResolver::haveSameStyles(&resolver, &resolver));
+}
+
+TEST_F(ScopedStyleResolverTest, HasSameStylesNonEmpty) {
+  document().body()->setInnerHTML("<div id=host1></div><div id=host2></div>");
+  Element* host1 = document().getElementById("host1");
+  Element* host2 = document().getElementById("host2");
+  ASSERT_TRUE(host1);
+  ASSERT_TRUE(host2);
+  ShadowRoot& root1 = attachShadow(*host1);
+  ShadowRoot& root2 = attachShadow(*host2);
+  root1.setInnerHTML("<style>::slotted(#dummy){color:pink}</style>");
+  root2.setInnerHTML("<style>::slotted(#dummy){color:pink}</style>");
+  document().view()->updateAllLifecyclePhases();
+  EXPECT_TRUE(ScopedStyleResolver::haveSameStyles(
+      &root1.ensureScopedStyleResolver(), &root2.ensureScopedStyleResolver()));
+}
+
+TEST_F(ScopedStyleResolverTest, HasSameStylesDifferentSheetCount) {
+  document().body()->setInnerHTML("<div id=host1></div><div id=host2></div>");
+  Element* host1 = document().getElementById("host1");
+  Element* host2 = document().getElementById("host2");
+  ASSERT_TRUE(host1);
+  ASSERT_TRUE(host2);
+  ShadowRoot& root1 = attachShadow(*host1);
+  ShadowRoot& root2 = attachShadow(*host2);
+  root1.setInnerHTML(
+      "<style>::slotted(#dummy){color:pink}</style><style>div{}</style>");
+  root2.setInnerHTML("<style>::slotted(#dummy){color:pink}</style>");
+  document().view()->updateAllLifecyclePhases();
+  EXPECT_FALSE(ScopedStyleResolver::haveSameStyles(
+      &root1.ensureScopedStyleResolver(), &root2.ensureScopedStyleResolver()));
+}
+
+TEST_F(ScopedStyleResolverTest, HasSameStylesCacheMiss) {
+  document().body()->setInnerHTML("<div id=host1></div><div id=host2></div>");
+  Element* host1 = document().getElementById("host1");
+  Element* host2 = document().getElementById("host2");
+  ASSERT_TRUE(host1);
+  ASSERT_TRUE(host2);
+  ShadowRoot& root1 = attachShadow(*host1);
+  ShadowRoot& root2 = attachShadow(*host2);
+  // Style equality is detected when StyleSheetContents is shared. That is only
+  // the case when the source text is the same. The comparison will fail when
+  // adding an extra space to one of the sheets.
+  root1.setInnerHTML("<style>::slotted(#dummy){color:pink}</style>");
+  root2.setInnerHTML("<style>::slotted(#dummy){ color:pink}</style>");
+  document().view()->updateAllLifecyclePhases();
+  EXPECT_FALSE(ScopedStyleResolver::haveSameStyles(
+      &root1.ensureScopedStyleResolver(), &root2.ensureScopedStyleResolver()));
+}
+
+}  // namespace blink