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 "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"
 #include "core/html/HTMLIFrameElement.h"
 #include "core/layout/api/LayoutViewItem.h"
 #include "core/page/FocusController.h"
 #include "core/page/Page.h"
 #include "core/paint/PaintLayer.h"
 #include "platform/testing/URLTestHelpers.h"
@@ skipping 755 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();

[ojan, 2016/10/31 19:37:10]

I know this isn't new in this patch, so obviously don't need to fix it as part
of this patch, but do we need these ForTesting methods? Can we just call
runPendingTasks instead?

e.g.
https://cs.chromium.org/chromium/src/third_party/WebKit/Source/web/tests/Defe...

I'm a huge fan of minimizing having testing-only methods in production code.

[ojan, 2016/10/31 19:38:27]

Oh, I see stefan already asked this. nm.

   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 64 matching lines @@
   LocalFrame* localFrame = toLocalFrame(secondFrameElement->contentFrame());
   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();
 }
 
+TEST_F(FrameThrottlingTest, AllowOneAnimationFrame) {

[ojan, 2016/10/31 19:37:10]

Did we end up finding always doing the first rAF to be necessary for back
compat?

[Sami, 2016/11/01 10:44:48]

I don't have definite proof that it's required -- I just wanted to document it
as an artifact of our implementation. I know Gmail does some tricksy stuff with
offscreen iframes so they could very well need this. In any case, changing this
would mean we'd have to start sending IObs notifications synchronously (which
IIRC you wanted to do anyway?), but let's leave that to a future patch :)

+  webView().settings()->setJavaScriptEnabled(true);
+
+  // Prepare a page with two cross origin frames (from the same origin so they
+  // are able to access eachother).
+  SimRequest mainResource("https://example.com/", "text/html");
+  SimRequest frameResource("https://thirdparty.com/frame.html", "text/html");
+  loadURL("https://example.com/");
+  mainResource.complete(
+      "<iframe id=frame style=\"position: fixed; top: -10000px\" "
+      "src='https://thirdparty.com/frame.html'></iframe>");
+
+  frameResource.complete(
+      "<script>"
+      "window.requestAnimationFrame(() => { window.didRaf = true; });"
+      "</script>");
+
+  auto* frameElement = toHTMLIFrameElement(document().getElementById("frame"));
+  compositeFrame();
+  EXPECT_TRUE(frameElement->contentDocument()->view()->canThrottleRendering());
+
+  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