[tracing] Adding class-wise memory statistics to blink gc memory dumps

Source/platform/heap/BlinkGCMemoryDumpProvider.cpp

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "Source/platform/heap/BlinkGCMemoryDumpProvider.h"
 
 #include "platform/heap/Handle.h"
 #include "public/platform/Platform.h"
 #include "public/platform/WebMemoryAllocatorDump.h"
@@ skipping 10 matching lines @@
 }
 
 BlinkGCMemoryDumpProvider::~BlinkGCMemoryDumpProvider()
 {
 }
 
 bool BlinkGCMemoryDumpProvider::onMemoryDump(blink::WebProcessMemoryDump* memoryDump)
 {
     Heap::collectGarbage(ThreadState::NoHeapPointersOnStack, ThreadState::TakeSnapshot, Heap::ForcedGC);
     String dumpName = String::format("blink_gc/thread_%lu", static_cast<unsigned long>(WTF::currentThread()));
-    WebMemoryAllocatorDump* allocatorDump = memoryDump->createMemoryAllocatorDump(dumpName);
+    WebMemoryAllocatorDump* allocatorDump = m_currentProcessMemoryDump->getMemoryAllocatorDump(dumpName);
+    if (!allocatorDump)
+        allocatorDump = m_currentProcessMemoryDump->createMemoryAllocatorDump(dumpName);
     allocatorDump->AddScalar("size", "bytes", Heap::allocatedSpace());
 
     dumpName.append("/allocated_objects");
-    WebMemoryAllocatorDump* objectsDump = memoryDump->createMemoryAllocatorDump(dumpName);
+    WebMemoryAllocatorDump* objectsDump = m_currentProcessMemoryDump->createMemoryAllocatorDump(dumpName);
     objectsDump->AddScalar("size", "bytes", Heap::allocatedObjectSize() + Heap::markedObjectSize());
     objectsDump->AddScalar("estimated_live_object_size", "bytes", Heap::estimatedLiveObjectSize());
 
     // Merge all dumps collected by Heap::collectGarbage.
     memoryDump->takeAllDumpsFrom(m_currentProcessMemoryDump.get());
     return true;
 }
 
 WebMemoryAllocatorDump* BlinkGCMemoryDumpProvider::createMemoryAllocatorDumpForCurrentGC(const String& absoluteName)
 {
     return m_currentProcessMemoryDump->createMemoryAllocatorDump(absoluteName);
 }
 
 void BlinkGCMemoryDumpProvider::clearProcessDumpForCurrentGC()
 {
     m_currentProcessMemoryDump->clear();
 }
 
 BlinkGCMemoryDumpProvider::BlinkGCMemoryDumpProvider()
     : m_currentProcessMemoryDump(adoptPtr(Platform::current()->createProcessMemoryDump()))
 {
 }
 
 } // namespace blink