Provide a method to remove inserted style sheet

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

 // Copyright 2016 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/dom/StyleEngine.h"
 
 #include <memory>
 #include "bindings/core/v8/V8BindingForCore.h"
 #include "core/css/CSSRuleList.h"
 #include "core/css/CSSStyleRule.h"
@@ skipping 69 matching lines @@
   GetDocument().body()->setInnerHTML(
       "<style>div { color: red }</style><div id='t1'>Green</div><div></div>");
   GetDocument().View()->UpdateAllLifecyclePhases();
 
   Element* t1 = GetDocument().getElementById("t1");
   ASSERT_TRUE(t1);
   ASSERT_TRUE(t1->GetComputedStyle());
   EXPECT_EQ(MakeRGB(255, 0, 0),
             t1->GetComputedStyle()->VisitedDependentColor(CSSPropertyColor));
 
-  unsigned before_count = GetStyleEngine().StyleForElementCount();
+  const unsigned initial_count = GetStyleEngine().StyleForElementCount();
 
-  StyleSheetContents* parsed_sheet =
+  StyleSheetContents* green_parsed_sheet =
       StyleSheetContents::Create(CSSParserContext::Create(GetDocument()));
-  parsed_sheet->ParseString("#t1 { color: green }");
-  GetStyleEngine().InjectAuthorSheet(parsed_sheet);
+  green_parsed_sheet->ParseString("#t1 { color: green }");
+  int green_css_id = GetStyleEngine().InjectAuthorSheet(green_parsed_sheet);
+  EXPECT_EQ(1, green_css_id);
+  EXPECT_EQ(1u, GetStyleEngine().InjectedAuthorStyleSheets().size());
   GetDocument().View()->UpdateAllLifecyclePhases();
 
-  unsigned after_count = GetStyleEngine().StyleForElementCount();
-  EXPECT_EQ(1u, after_count - before_count);
+  EXPECT_EQ(1u, GetStyleEngine().StyleForElementCount() - initial_count);
 
   ASSERT_TRUE(t1->GetComputedStyle());
   EXPECT_EQ(MakeRGB(0, 128, 0),
             t1->GetComputedStyle()->VisitedDependentColor(CSSPropertyColor));
+
+  StyleSheetContents* blue_parsed_sheet =
+      StyleSheetContents::Create(CSSParserContext::Create(GetDocument()));
+  blue_parsed_sheet->ParseString("#t1 { color: blue }");
+  int blue_css_id = GetStyleEngine().InjectAuthorSheet(blue_parsed_sheet);
+  EXPECT_EQ(2, blue_css_id);
+  EXPECT_EQ(2u, GetStyleEngine().InjectedAuthorStyleSheets().size());
+  GetDocument().View()->UpdateAllLifecyclePhases();
+
+  EXPECT_EQ(2u, GetStyleEngine().StyleForElementCount() - initial_count);
+
+  ASSERT_TRUE(t1->GetComputedStyle());
+  EXPECT_EQ(MakeRGB(0, 0, 255),
+            t1->GetComputedStyle()->VisitedDependentColor(CSSPropertyColor));
+
+  EXPECT_TRUE(GetStyleEngine().RemoveInjectedAuthorSheet(green_css_id));
+  EXPECT_EQ(1u, GetStyleEngine().InjectedAuthorStyleSheets().size());
+  GetDocument().View()->UpdateAllLifecyclePhases();
+  EXPECT_EQ(3u, GetStyleEngine().StyleForElementCount() - initial_count);
+  ASSERT_TRUE(t1->GetComputedStyle());
+  EXPECT_EQ(MakeRGB(0, 0, 255),
+            t1->GetComputedStyle()->VisitedDependentColor(CSSPropertyColor));
+
+  EXPECT_TRUE(GetStyleEngine().RemoveInjectedAuthorSheet(blue_css_id));
+  EXPECT_EQ(0u, GetStyleEngine().InjectedAuthorStyleSheets().size());
+  GetDocument().View()->UpdateAllLifecyclePhases();
+  EXPECT_EQ(4u, GetStyleEngine().StyleForElementCount() - initial_count);
+  ASSERT_TRUE(t1->GetComputedStyle());
+  EXPECT_EQ(MakeRGB(255, 0, 0),
+            t1->GetComputedStyle()->VisitedDependentColor(CSSPropertyColor));
 }
 
 TEST_F(StyleEngineTest, TextToSheetCache) {
   HTMLStyleElement* element = HTMLStyleElement::Create(GetDocument(), false);
 
   String sheet_text("div {}");
   TextPosition min_pos = TextPosition::MinimumPosition();
   StyleEngineContext context;
 
   CSSStyleSheet* sheet1 =
@@ skipping 437 matching lines @@
       "</style>"
       "<div id='t1'></div>"
       "<span></span>");
 
   GetStyleEngine().UpdateActiveStyle();
   EXPECT_FALSE(GetDocument().ChildNeedsStyleInvalidation());
   EXPECT_FALSE(GetDocument().NeedsStyleInvalidation());
 }
 
 }  // namespace blink