Revert of Let FrameView track object paint invalidations

third_party/WebKit/Source/core/layout/compositing/PaintLayerCompositor.cpp

Index: third_party/WebKit/Source/core/layout/compositing/PaintLayerCompositor.cpp
diff --git a/third_party/WebKit/Source/core/layout/compositing/PaintLayerCompositor.cpp b/third_party/WebKit/Source/core/layout/compositing/PaintLayerCompositor.cpp
index 147be3bb66ff624d2dbd95c2c72bb5e50a57349e..ca9b72a3583c5c5b37e395d0ddad3e7d26f09efc 100644
--- a/third_party/WebKit/Source/core/layout/compositing/PaintLayerCompositor.cpp
+++ b/third_party/WebKit/Source/core/layout/compositing/PaintLayerCompositor.cpp
@@ -55,7 +55,6 @@
 #include "core/paint/FramePainter.h"
 #include "core/paint/TransformRecorder.h"
 #include "platform/Histogram.h"
-#include "platform/JSONValues.h"
 #include "platform/RuntimeEnabledFeatures.h"
 #include "platform/ScriptForbiddenScope.h"
 #include "platform/TraceEvent.h"
@@ -647,12 +646,12 @@
     return false;
 }
 
-PassRefPtr<JSONObject> PaintLayerCompositor::layerTreeAsJSON(LayerTreeFlags flags) const
+String PaintLayerCompositor::layerTreeAsText(LayerTreeFlags flags)
 {
     ASSERT(lifecycle().state() >= DocumentLifecycle::PaintInvalidationClean || m_layoutView.frameView()->shouldThrottleRendering());
 
     if (!m_rootContentLayer)
-        return nullptr;
+        return String();
 
     // We skip dumping the scroll and clip layers to keep layerTreeAsText output
     // similar between platforms (unless we explicitly request dumping from the
@@ -661,7 +660,7 @@
     if (flags & LayerTreeIncludesRootLayer)
         rootLayer = rootGraphicsLayer();
 
-    return rootLayer->layerTreeAsJSON(flags);
+    return rootLayer->layerTreeAsText(flags);
 }
 
 PaintLayerCompositor* PaintLayerCompositor::frameContentsCompositor(LayoutPart* layoutObject)