Add a FOUC painting test.

Source/web/tests/sim/SimCompositor.cpp

Index: Source/web/tests/sim/SimCompositor.cpp
diff --git a/Source/web/tests/sim/SimCompositor.cpp b/Source/web/tests/sim/SimCompositor.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..da70fbcdc4e65a8f364ae187f0264fd437190e66
--- /dev/null
+++ b/Source/web/tests/sim/SimCompositor.cpp
@@ -0,0 +1,92 @@
+// 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 "config.h"
+#include "web/tests/sim/SimCompositor.h"
+
+#include "core/frame/FrameView.h"
+#include "core/layout/LayoutView.h"
+#include "core/layout/compositing/CompositedDeprecatedPaintLayerMapping.h"
+#include "core/paint/DeprecatedPaintLayer.h"
+#include "platform/graphics/ContentLayerDelegate.h"
+#include "public/platform/WebRect.h"
+#include "web/WebLocalFrameImpl.h"
+#include "web/WebViewImpl.h"
+#include "web/tests/sim/SimDisplayItemList.h"
+#include "web/tests/sim/SimLayerTreeView.h"
+#include "wtf/CurrentTime.h"
+
+namespace blink {
+
+static void paintLayers(DeprecatedPaintLayer& layer, SimDisplayItemList& displayList)
+{
+    if (layer.compositingState() == PaintsIntoOwnBacking) {
+        CompositedDeprecatedPaintLayerMapping* mapping = layer.compositedDeprecatedPaintLayerMapping();
+        GraphicsLayer* graphicsLayer = mapping->mainGraphicsLayer();
+        if (graphicsLayer->hasTrackedPaintInvalidations()) {
+            ContentLayerDelegate* delegate = graphicsLayer->contentLayerDelegateForTesting();
+            delegate->paintContents(&displayList, WebRect(0, 0, layer.size().width(), layer.size().height()));
+            graphicsLayer->resetTrackedPaintInvalidations();
+        }
+    }
+    for (DeprecatedPaintLayer* child = layer.firstChild(); child; child = child->nextSibling())
+        paintLayers(*child, displayList);
+}
+
+static void paintFrames(LocalFrame& root, SimDisplayItemList& displayList)
+{
+    for (Frame* frame = &root; frame; frame = frame->tree().traverseNext(&root)) {
+        if (!frame->isLocalFrame())
+            continue;
+        DeprecatedPaintLayer* layer = toLocalFrame(frame)->view()->layoutView()->layer();
+        paintLayers(*layer, displayList);
+    }
+}
+
+SimCompositor::SimCompositor(SimLayerTreeView& layerTreeView)
+    : m_layerTreeView(&layerTreeView)
+    , m_webViewImpl(0)
+    , m_lastFrameTimeMonotonic(0)
+{
+    FrameView::setInitialTracksPaintInvalidationsForTesting(true);
+    // Disable the debug red fill so the output display list doesn't differ in
+    // size in Release vs Debug builds.
+    GraphicsLayer::setDrawDebugRedFillForTesting(false);
+}
+
+SimCompositor::~SimCompositor()
+{
+    FrameView::setInitialTracksPaintInvalidationsForTesting(false);
+    GraphicsLayer::setDrawDebugRedFillForTesting(true);
+}
+
+void SimCompositor::setWebViewImpl(WebViewImpl& webViewImpl)
+{
+    m_webViewImpl = &webViewImpl;
+}
+
+SimDisplayItemList SimCompositor::beginFrame()
+{
+    ASSERT(m_webViewImpl);
+    ASSERT(!m_layerTreeView->deferCommits());
+    ASSERT(m_layerTreeView->needsAnimate());
+
+    // Always advance the time as if the compositor was running at 60fps.
+    m_lastFrameTimeMonotonic = monotonicallyIncreasingTime() + 0.016;
+
+    WebBeginFrameArgs args(m_lastFrameTimeMonotonic, 0, 0);
+    m_webViewImpl->beginFrame(args);
+    m_webViewImpl->layout();
+
+    LocalFrame* root = m_webViewImpl->mainFrameImpl()->frame();
+
+    SimDisplayItemList displayList;
+    paintFrames(*root, displayList);
+
+    m_layerTreeView->clearNeedsAnimate();
+
+    return displayList;
+}
+
+} // namespace blink