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

Source/platform/graphics/paint/ClipRecorder.cpp

Index: Source/platform/graphics/paint/ClipRecorder.cpp
diff --git a/Source/platform/graphics/paint/ClipRecorder.cpp b/Source/platform/graphics/paint/ClipRecorder.cpp
index 89471735da5e17201d0753c382e0102209552f18..9dd25b5806f85c4e9791da779e02f3df9399a9dc 100644
--- a/Source/platform/graphics/paint/ClipRecorder.cpp
+++ b/Source/platform/graphics/paint/ClipRecorder.cpp
@@ -12,33 +12,50 @@
 
 namespace blink {
 
-ClipRecorder::ClipRecorder(GraphicsContext& context, const DisplayItemClientWrapper& client, DisplayItem::Type type, const LayoutRect& clipRect, SkRegion::Op operation)
+ClipRecorder::ClipRecorder(GraphicsContext& context, const DisplayItemClientWrapper& client, DisplayItem::Type type)
     : m_client(client)
     , m_context(context)
     , m_type(type)
+    , m_engaged(false)
+{
+}
+
+ClipRecorder::ClipRecorder(GraphicsContext& context, const DisplayItemClientWrapper& client, DisplayItem::Type type, const LayoutRect& clipRect, SkRegion::Op operation)
+    : ClipRecorder(context, client, type)
 {
+    begin(clipRect, operation);
+}
+
+ClipRecorder::~ClipRecorder()
+{
+    if (!m_engaged)
+        return;
+
+    DisplayItem::Type endType = DisplayItem::clipTypeToEndClipType(m_type);
     if (RuntimeEnabledFeatures::slimmingPaintEnabled()) {
         ASSERT(m_context.displayItemList());
         if (m_context.displayItemList()->displayItemConstructionIsDisabled())
             return;
-        m_context.displayItemList()->add(ClipDisplayItem::create(m_client, type, pixelSnappedIntRect(clipRect), operation));
+        m_context.displayItemList()->add(EndClipDisplayItem::create(m_client, endType));
     } else {
-        ClipDisplayItem clipDisplayItem(m_client, type, pixelSnappedIntRect(clipRect), operation);
-        clipDisplayItem.replay(m_context);
+        EndClipDisplayItem endClipDisplayItem(m_client, endType);
+        endClipDisplayItem.replay(m_context);
     }
 }
 
-ClipRecorder::~ClipRecorder()
+void ClipRecorder::begin(const LayoutRect& clipRect, SkRegion::Op operation)
 {
-    DisplayItem::Type endType = DisplayItem::clipTypeToEndClipType(m_type);
+    ASSERT(!m_engaged);
+    m_engaged = true;
+
     if (RuntimeEnabledFeatures::slimmingPaintEnabled()) {
         ASSERT(m_context.displayItemList());
         if (m_context.displayItemList()->displayItemConstructionIsDisabled())
             return;
-        m_context.displayItemList()->add(EndClipDisplayItem::create(m_client, endType));
+        m_context.displayItemList()->add(ClipDisplayItem::create(m_client, m_type, pixelSnappedIntRect(clipRect), operation));
     } else {
-        EndClipDisplayItem endClipDisplayItem(m_client, endType);
-        endClipDisplayItem.replay(m_context);
+        ClipDisplayItem clipDisplayItem(m_client, m_type, pixelSnappedIntRect(clipRect), operation);
+        clipDisplayItem.replay(m_context);
     }
 }