Use intersection observer to control frame throttling

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

Index: third_party/WebKit/Source/web/tests/FrameThrottlingTest.cpp
diff --git a/third_party/WebKit/Source/web/tests/FrameThrottlingTest.cpp b/third_party/WebKit/Source/web/tests/FrameThrottlingTest.cpp
index b2e6e095f0f9840e161dccf0f2c46bc41dcfda51..7e022a42b2eabb0f0b29719a3d16f0b2ced210ff 100644
--- a/third_party/WebKit/Source/web/tests/FrameThrottlingTest.cpp
+++ b/third_party/WebKit/Source/web/tests/FrameThrottlingTest.cpp
@@ -3,6 +3,7 @@
 // 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"
@@ -778,7 +779,7 @@ TEST_F(FrameThrottlingTest, ThrottleSubtreeAtomically) {
   // 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());
@@ -786,10 +787,34 @@ TEST_F(FrameThrottlingTest, ThrottleSubtreeAtomically) {
   // 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) {
@@ -874,4 +899,33 @@ TEST_F(FrameThrottlingTest, SynchronousLayoutInAnimationFrameCallback) {
   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