Update styleSheets list in import without active style update.

third_party/WebKit/Source/web/tests/HTMLImportSheetsTest.cpp

Index: third_party/WebKit/Source/web/tests/HTMLImportSheetsTest.cpp
diff --git a/third_party/WebKit/Source/web/tests/HTMLImportSheetsTest.cpp b/third_party/WebKit/Source/web/tests/HTMLImportSheetsTest.cpp
index b870d15cd0ef30ca98956f486914c6e57ca6c2b6..36c75d90f34c129c1e6a398de8e7c98025fd2d2d 100644
--- a/third_party/WebKit/Source/web/tests/HTMLImportSheetsTest.cpp
+++ b/third_party/WebKit/Source/web/tests/HTMLImportSheetsTest.cpp
@@ -35,4 +35,24 @@ TEST_F(HTMLImportSheetsTest, NeedsActiveStyleUpdate) {
   EXPECT_FALSE(import_doc->GetStyleEngine().NeedsActiveStyleUpdate());
 }
 
+TEST_F(HTMLImportSheetsTest, UpdateStyleSheetList) {
+  SimRequest main_resource("https://example.com/", "text/html");
+  SimRequest import_resource("https://example.com/import.html", "text/html");
+
+  LoadURL("https://example.com/");
+  main_resource.Complete("<link id=link rel=import href=import.html>");
+  import_resource.Complete("<style>div{}</style>");
+
+  EXPECT_TRUE(GetDocument().GetStyleEngine().NeedsActiveStyleUpdate());
+  Document* import_doc =
+      toHTMLLinkElement(GetDocument().getElementById("link"))->import();
+  ASSERT_TRUE(import_doc);
+  EXPECT_TRUE(import_doc->GetStyleEngine().NeedsActiveStyleUpdate());
+
+  import_doc->GetStyleEngine().StyleSheetsForStyleSheetList(*import_doc);
+
+  EXPECT_TRUE(GetDocument().GetStyleEngine().NeedsActiveStyleUpdate());
+  EXPECT_FALSE(import_doc->GetStyleEngine().NeedsActiveStyleUpdate());
+}
+
 }  // namespace blink