Allow throttling in painting microbenchmark

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 60faa0b895dc7efc0cd86d439d21682d141153f4..355b06b78cab3b15d5354e3f22a4824b1da5ecd5 100644
--- a/third_party/WebKit/Source/web/tests/FrameThrottlingTest.cpp
+++ b/third_party/WebKit/Source/web/tests/FrameThrottlingTest.cpp
@@ -11,6 +11,7 @@
 #include "core/paint/PaintLayer.h"
 #include "platform/testing/URLTestHelpers.h"
 #include "platform/testing/UnitTestHelpers.h"
+#include "public/platform/WebDisplayItemList.h"
 #include "public/platform/WebLayer.h"
 #include "public/web/WebHitTestResult.h"
 #include "public/web/WebSettings.h"
@@ -22,12 +23,35 @@
 #include "web/tests/sim/SimRequest.h"
 #include "web/tests/sim/SimTest.h"
 
+using testing::_;
+
 namespace blink {
 
 using namespace HTMLNames;
 
 // NOTE: This test uses <iframe sandbox> to create cross origin iframes.
 
+namespace {
+
+class MockWebDisplayItemList : public WebDisplayItemList {
+public:
+    ~MockWebDisplayItemList() override {}
+
+    MOCK_METHOD2(appendDrawingItem, void(const WebRect&, sk_sp<const SkPicture>));
+};
+
+void paintRecursively(GraphicsLayer* layer, WebDisplayItemList* displayItems)
+{
+    if (layer->drawsContent()) {
+        layer->setNeedsDisplay();
+        layer->contentLayerDelegateForTesting()->paintContents(displayItems, ContentLayerDelegate::PaintDefaultBehaviorForTest);
+    }
+    for (const auto& child : layer->children())
+        paintRecursively(child, displayItems);
+}
+
+} // namespace
+
 class FrameThrottlingTest : public SimTest {
 protected:
     FrameThrottlingTest()
@@ -621,4 +645,36 @@ TEST_F(FrameThrottlingTest, ThrottledEventHandlerIgnored)
     EXPECT_EQ(1u, touchHandlerRegionSize());
 }
 
+TEST_F(FrameThrottlingTest, PaintingViaContentLayerDelegateIsThrottled)
+{
+    webView().settings()->setAcceleratedCompositingEnabled(true);
+    webView().settings()->setPreferCompositingToLCDTextEnabled(true);
+
+    // Create a hidden frame which is throttled.
+    SimRequest mainResource("https://example.com/", "text/html");
+    SimRequest frameResource("https://example.com/iframe.html", "text/html");
+
+    loadURL("https://example.com/");
+    mainResource.complete("<iframe id=frame sandbox src=iframe.html></iframe>");
+    frameResource.complete("throttled");
+    compositeFrame();
+
+    // Move the frame offscreen to throttle it and make sure it is backed by a
+    // graphics layer.
+    auto* frameElement = toHTMLIFrameElement(document().getElementById("frame"));
+    frameElement->setAttribute(styleAttr, "transform: translateY(480px) translateZ(0px)");
+    EXPECT_FALSE(frameElement->contentDocument()->view()->canThrottleRendering());
+    compositeFrame();
+    EXPECT_TRUE(frameElement->contentDocument()->view()->canThrottleRendering());
+
+    // If painting of the iframe is throttled, we should only receive two
+    // drawing items.
+    MockWebDisplayItemList displayItems;
+    EXPECT_CALL(displayItems, appendDrawingItem(_, _))
+        .Times(2);
+
+    GraphicsLayer* layer = webView().rootGraphicsLayer();
+    paintRecursively(layer, &displayItems);

[ojan, 2016/04/28 21:47:27]

Specifically, this is not a thing that can happen on the web, right? (painting
outside of a lifecycle update)

[Xianzhu, 2016/04/28 21:56:32]

Right.

However, I think this is why we call rasterize_and_record_micro a micro
benchmark: it provides several controlled modes to simulate extreme conditions
(e.g. no caching, no subsequence caching but have display item caching, no
painting, etc.) to expose micro aspects of painting performance.

For painting performance in real scenarios, we can use the UMA performance
measurements. We can also collect the UMA performance measurements in a
benchmark.

+}
+
 } // namespace blink