FrameView: Don't throttle display:none frames

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

 // Copyright 2015 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 "bindings/core/v8/ScriptController.h"
 #include "bindings/core/v8/ScriptSourceCode.h"
 #include "core/dom/Document.h"
 #include "core/dom/Element.h"
 #include "core/frame/FrameView.h"
 #include "core/frame/LocalFrame.h"
@@ skipping 959 matching lines @@
   frameElement->setAttribute(HTMLNames::styleAttr, "");
   // The first update unthrottles the frame, the second actually update layout
   // and paint properties etc.
   compositeFrame();
   compositeFrame();
   EXPECT_FALSE(frameDocument->view()->canThrottleRendering());
   EXPECT_EQ(TransformationMatrix().translate(0, 20),
             innerDiv->layoutObject()->paintProperties()->transform()->matrix());
 }
 
+TEST_F(FrameThrottlingTest, DisplayNoneNotThrottled) {
+  SimRequest mainResource("https://example.com/", "text/html");
+
+  loadURL("https://example.com/");
+  mainResource.complete(
+      "<style>iframe { transform: translateY(480px); }</style>"
+      "<iframe sandbox id=frame></iframe>");
+
+  auto* frameElement = toHTMLIFrameElement(document().getElementById("frame"));
+  auto* frameDocument = frameElement->contentDocument();
+
+  // Initially the frame is throttled as it is offscreen.
+  compositeFrame();
+  EXPECT_TRUE(frameDocument->view()->canThrottleRendering());
+
+  // Setting display:none unthrottles the frame.
+  frameElement->setAttribute(styleAttr, "display: none");
+  compositeFrame();
+  EXPECT_FALSE(frameDocument->view()->canThrottleRendering());
+}
+
 }  // namespace blink