Revert of Remove begin/end subseq. display items, and store on PaintController instead.

third_party/WebKit/Source/platform/graphics/paint/SubsequenceRecorder.cpp

Index: third_party/WebKit/Source/platform/graphics/paint/SubsequenceRecorder.cpp
diff --git a/third_party/WebKit/Source/platform/graphics/paint/SubsequenceRecorder.cpp b/third_party/WebKit/Source/platform/graphics/paint/SubsequenceRecorder.cpp
index 0a67e06fc58ad81cbca90df64a1eadc9650d5c58..371baf0346f88df6057e1a46a2d4b6e420d023e0 100644
--- a/third_party/WebKit/Source/platform/graphics/paint/SubsequenceRecorder.cpp
+++ b/third_party/WebKit/Source/platform/graphics/paint/SubsequenceRecorder.cpp
@@ -7,6 +7,7 @@
 #include "platform/RuntimeEnabledFeatures.h"
 #include "platform/graphics/GraphicsContext.h"
 #include "platform/graphics/paint/PaintController.h"
+#include "platform/graphics/paint/SubsequenceDisplayItem.h"
 
 namespace blink {
 
@@ -19,27 +20,26 @@
     return;
 
   m_beginSubsequenceIndex = m_paintController.newDisplayItemList().size();
-
-#if CHECK_DISPLAY_ITEM_CLIENT_ALIVENESS
-  m_paintController.beginSubsequence(m_client);
-#endif
+  m_paintController.createAndAppend<BeginSubsequenceDisplayItem>(m_client);
 }
 
 SubsequenceRecorder::~SubsequenceRecorder() {
-#if CHECK_DISPLAY_ITEM_CLIENT_ALIVENESS
-  m_paintController.endSubsequence();
-#endif
-
   if (m_paintController.displayItemConstructionIsDisabled())
     return;
 
-  // Skip empty subsequences.
-  if (m_paintController.newDisplayItemList().size() == m_beginSubsequenceIndex)
-    return;
+  if (m_paintController.lastDisplayItemIsNoopBegin()) {
+    ASSERT(m_beginSubsequenceIndex ==
+           m_paintController.newDisplayItemList().size() - 1);
+    // Remove uncacheable no-op BeginSubsequence/EndSubsequence pairs.
+    // Don't remove cacheable no-op pairs because we need to match them later
+    // with CachedSubsequences.
+    if (m_paintController.newDisplayItemList().last().skippedCache()) {
+      m_paintController.removeLastDisplayItem();
+      return;
+    }
+  }
 
-  m_paintController.addCachedSubsequence(
-      m_client, m_beginSubsequenceIndex,
-      m_paintController.newDisplayItemList().size() - 1);
+  m_paintController.createAndAppend<EndSubsequenceDisplayItem>(m_client);
 }
 
 }  // namespace blink