Replace RenderArena with PartitionAlloc.

Source/core/inspector/InspectorMemoryAgent.cpp

Index: Source/core/inspector/InspectorMemoryAgent.cpp
diff --git a/Source/core/inspector/InspectorMemoryAgent.cpp b/Source/core/inspector/InspectorMemoryAgent.cpp
index 017c3626fe3a17417d5c8fe7267c9143d41b6654..6fa13c554019f7298db1e597db1328cb1fbabe3f 100644
--- a/Source/core/inspector/InspectorMemoryAgent.cpp
+++ b/Source/core/inspector/InspectorMemoryAgent.cpp
@@ -46,6 +46,7 @@
 #include "core/page/Frame.h"
 #include "core/page/Page.h"
 #include "core/platform/MemoryUsageSupport.h"
+#include "core/platform/Partitions.h"
 #include <wtf/ArrayBufferView.h>
 #include <wtf/HashSet.h>
 #include <wtf/MemoryInstrumentationArrayBufferView.h>
@@ -74,7 +75,7 @@ public:
         m_sizesMap = sizesMap;
 
         // FIXME: We filter out Rendering type because the coverage is not good enough at the moment
-        // and report RenderArena size instead.
+        // and report rendering partition size instead.
         for (TypeNameToSizeMap::iterator i = m_sizesMap.begin(); i != m_sizesMap.end(); ++i) {
             if (i->key == PlatformMemoryTypes::Rendering) {
                 m_sizesMap.remove(i);
@@ -201,12 +202,14 @@ static void reportJSHeapInfo(WTF::MemoryInstrumentationClient& memoryInstrumenta
     memoryInstrumentationClient.countObjectSize(0, WebCoreMemoryTypes::JSHeapUnused, info.totalJSHeapSize - info.usedJSHeapSize);
 }
 
-static void reportRenderTreeInfo(WTF::MemoryInstrumentationClient& memoryInstrumentationClient, Page* page)
+static void reportRenderTreeInfo(WTF::MemoryInstrumentationClient& memoryInstrumentationClient, Page*)
 {
-    ArenaSize arenaSize = page->renderTreeSize();
+    size_t renderTreeSize = 0;
+#if ENABLE(PARTITION_ALLOC)
+    renderTreeSize = partitionAllocGetUsedPagesSize(*Partitions::getRenderingPartition());
+#endif
 
-    memoryInstrumentationClient.countObjectSize(0, WebCoreMemoryTypes::RenderTreeUsed, arenaSize.treeSize);
-    memoryInstrumentationClient.countObjectSize(0, WebCoreMemoryTypes::RenderTreeUnused, arenaSize.allocated - arenaSize.treeSize);
+    memoryInstrumentationClient.countObjectSize(0, WebCoreMemoryTypes::RenderTreeUsed, renderTreeSize);
 }
 
 namespace {