Only scroll on main if the targeted frames need to scroll on main

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 478 matching lines @@
   // The fixed background in the throttled sub frame should not cause main
   // thread scrolling.
   EXPECT_FALSE(document().view()->shouldScrollOnMainThread());
 
   // Make the frame visible by changing its transform. This doesn't cause a
   // layout, but should still unthrottle the frame.
   frameElement->setAttribute(styleAttr, "transform: translateY(0px)");
   compositeFrame();
   EXPECT_FALSE(frameElement->contentDocument()->view()->canThrottleRendering());
   // The fixed background in the throttled sub frame should be considered.
-  EXPECT_TRUE(document().view()->shouldScrollOnMainThread());
+  EXPECT_TRUE(
+      frameElement->contentDocument()->view()->shouldScrollOnMainThread());
+  EXPECT_FALSE(document().view()->shouldScrollOnMainThread());
 }
 
 TEST_F(FrameThrottlingTest, ScrollingCoordinatorShouldSkipThrottledLayer) {
   webView().settings()->setJavaScriptEnabled(true);
   webView().settings()->setAcceleratedCompositingEnabled(true);
   webView().settings()->setPreferCompositingToLCDTextEnabled(true);
 
   // Create a hidden frame which is throttled and has a touch handler inside a
   // composited layer.
   SimRequest mainResource("https://example.com/", "text/html");
@@ skipping 412 matching lines @@
 
   LocalFrame* localFrame = toLocalFrame(frameElement->contentFrame());
   v8::HandleScope scope(v8::Isolate::GetCurrent());
   v8::Local<v8::Value> result =
       localFrame->script().executeScriptInMainWorldAndReturnValue(
           ScriptSourceCode("window.didRaf;"));
   EXPECT_TRUE(result->IsTrue());
 }
 
 }  // namespace blink