Use intersection observer to control frame throttling

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 "core/dom/Document.h"
 #include "core/dom/Element.h"
 #include "core/frame/FrameView.h"
 #include "core/frame/LocalFrame.h"
 #include "core/html/HTMLIFrameElement.h"
@@ skipping 760 matching lines @@
   EXPECT_FALSE(frameElement->contentDocument()->view()->canThrottleRendering());
   EXPECT_FALSE(
       childFrameElement->contentDocument()->view()->canThrottleRendering());
 
   // Only run the intersection observer for the parent frame. Both frames
   // should immediately become throttled. This simulates the case where a task
   // such as BeginMainFrame runs in the middle of dispatching intersection
   // observer notifications.
   frameElement->contentDocument()
       ->view()
-      ->notifyRenderThrottlingObserversForTesting();
+      ->updateRenderThrottlingStatusForTesting();
   EXPECT_TRUE(frameElement->contentDocument()->view()->canThrottleRendering());
   EXPECT_TRUE(
       childFrameElement->contentDocument()->view()->canThrottleRendering());
 
   // Both frames should still be throttled after the second notification.
   childFrameElement->contentDocument()
       ->view()
-      ->notifyRenderThrottlingObserversForTesting();
+      ->updateRenderThrottlingStatusForTesting();
   EXPECT_TRUE(frameElement->contentDocument()->view()->canThrottleRendering());
   EXPECT_TRUE(
       childFrameElement->contentDocument()->view()->canThrottleRendering());
+
+  // Move the frame back on screen but don't update throttling yet.
+  frameElement->setAttribute(styleAttr, "transform: translateY(0px)");
+  compositor().beginFrame();
+  EXPECT_TRUE(frameElement->contentDocument()->view()->canThrottleRendering());
+  EXPECT_TRUE(
+      childFrameElement->contentDocument()->view()->canThrottleRendering());
+
+  // Update throttling for the child. It should remain throttled because the
+  // parent is still throttled.
+  childFrameElement->contentDocument()
+      ->view()
+      ->updateRenderThrottlingStatusForTesting();
+  EXPECT_TRUE(frameElement->contentDocument()->view()->canThrottleRendering());
+  EXPECT_TRUE(
+      childFrameElement->contentDocument()->view()->canThrottleRendering());
+
+  // Updating throttling on the parent should unthrottle both frames.
+  frameElement->contentDocument()
+      ->view()
+      ->updateRenderThrottlingStatusForTesting();
+  EXPECT_FALSE(frameElement->contentDocument()->view()->canThrottleRendering());
+  EXPECT_FALSE(
+      childFrameElement->contentDocument()->view()->canThrottleRendering());
 }
 
 TEST_F(FrameThrottlingTest, SkipPaintingLayersInThrottledFrames) {
   webView().settings()->setAcceleratedCompositingEnabled(true);
   webView().settings()->setPreferCompositingToLCDTextEnabled(true);
 
   SimRequest mainResource("https://example.com/", "text/html");
   SimRequest frameResource("https://example.com/iframe.html", "text/html");
 
   loadURL("https://example.com/");
@@ skipping 65 matching lines @@
   localFrame->script().executeScriptInMainWorld(
       "window.requestAnimationFrame(function() {\n"
       "  var throttledFrame = window.parent.frames.first;\n"
       "  throttledFrame.document.documentElement.style = 'margin: 50px';\n"
       "  throttledFrame.document.querySelector('#d').getBoundingClientRect();\n"
       "});\n");
   compositeFrame();
 }
 
 }  // namespace blink