Allow certain SP recorder classes to defer their "begin" operation.

Source/core/paint/FloatClipRecorder.cpp

Index: Source/core/paint/FloatClipRecorder.cpp
diff --git a/Source/core/paint/FloatClipRecorder.cpp b/Source/core/paint/FloatClipRecorder.cpp
index 8797c065c2010645b3bf154ea8cc24d13bdd432e..7a77f9837b7a36736de93e6fee48423b5bd5fa0f 100644
--- a/Source/core/paint/FloatClipRecorder.cpp
+++ b/Source/core/paint/FloatClipRecorder.cpp
@@ -12,33 +12,49 @@
 
 namespace blink {
 
-FloatClipRecorder::FloatClipRecorder(GraphicsContext& context, const DisplayItemClientWrapper& client, PaintPhase paintPhase, const FloatRect& clipRect)
+FloatClipRecorder::FloatClipRecorder(GraphicsContext& context, const DisplayItemClientWrapper& client, PaintPhase paintPhase)
     : m_context(context)
     , m_client(client)
     , m_clipType(DisplayItem::paintPhaseToFloatClipType(paintPhase))
 {
+}
+
+FloatClipRecorder::FloatClipRecorder(GraphicsContext& context, const DisplayItemClientWrapper& client, PaintPhase paintPhase, const FloatRect& clipRect)
+    : FloatClipRecorder(context, client, paintPhase)
+{
+    begin(clipRect);
+}
+
+FloatClipRecorder::~FloatClipRecorder()
+{
+    if (!m_engaged)
+        return;
+
+    DisplayItem::Type endType = DisplayItem::floatClipTypeToEndFloatClipType(m_clipType);
     if (RuntimeEnabledFeatures::slimmingPaintEnabled()) {
         ASSERT(m_context.displayItemList());
         if (m_context.displayItemList()->displayItemConstructionIsDisabled())
             return;
-        m_context.displayItemList()->add(FloatClipDisplayItem::create(m_client, m_clipType, clipRect));
+        m_context.displayItemList()->add(EndFloatClipDisplayItem::create(m_client, endType));
     } else {
-        FloatClipDisplayItem clipDisplayItem(m_client, m_clipType, clipRect);
-        clipDisplayItem.replay(m_context);
+        EndFloatClipDisplayItem endClipDisplayItem(m_client, endType);
+        endClipDisplayItem.replay(m_context);
     }
 }
 
-FloatClipRecorder::~FloatClipRecorder()
+void FloatClipRecorder::begin(const FloatRect& clipRect)
 {
-    DisplayItem::Type endType = DisplayItem::floatClipTypeToEndFloatClipType(m_clipType);
+    ASSERT(!m_engaged);
+    m_engaged = true;
+
     if (RuntimeEnabledFeatures::slimmingPaintEnabled()) {
         ASSERT(m_context.displayItemList());
         if (m_context.displayItemList()->displayItemConstructionIsDisabled())
             return;
-        m_context.displayItemList()->add(EndFloatClipDisplayItem::create(m_client, endType));
+        m_context.displayItemList()->add(FloatClipDisplayItem::create(m_client, m_clipType, clipRect));
     } else {
-        EndFloatClipDisplayItem endClipDisplayItem(m_client, endType);
-        endClipDisplayItem.replay(m_context);
+        FloatClipDisplayItem clipDisplayItem(m_client, m_clipType, clipRect);
+        clipDisplayItem.replay(m_context);
     }
 }