Skip creating spdy_session_pool dump if pool is empty in MemoryDumpProvider

net/spdy/spdy_session_pool.cc

 // Copyright (c) 2012 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 "net/spdy/spdy_session_pool.h"
 
 #include <utility>
 
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
@@ skipping 353 matching lines @@
   CloseCurrentSessions(ERR_NETWORK_CHANGED);
 }
 
 void SpdySessionPool::OnCertDBChanged(const X509Certificate* cert) {
   CloseCurrentSessions(ERR_CERT_DATABASE_CHANGED);
 }
 
 void SpdySessionPool::DumpMemoryStats(
     base::trace_event::ProcessMemoryDump* pmd,
     const std::string& parent_dump_absolute_name) const {
-  std::string dump_name = base::StringPrintf("%s/spdy_session_pool",
-                                             parent_dump_absolute_name.c_str());
-  base::trace_event::MemoryAllocatorDump* dump =
-      pmd->CreateAllocatorDump(dump_name);
   size_t total_size = 0;
   size_t buffer_size = 0;
   size_t cert_count = 0;
   size_t serialized_cert_size = 0;
   size_t num_active_sessions = 0;
   for (const auto& session : sessions_) {
     StreamSocket::SocketMemoryStats stats;
     bool is_session_active = false;
     session->DumpMemoryStats(&stats, &is_session_active);
     total_size += stats.total_size;
     buffer_size += stats.buffer_size;
     cert_count += stats.cert_count;
     serialized_cert_size += stats.serialized_cert_size;
     if (is_session_active)
       num_active_sessions++;
   }
+  if (sessions_.empty())

[ssid, 2017/01/20 21:35:58]

Could do this at the start of the function.  But why do we want to record if
total is 0, but sessions_ is not empty?

[xunjieli, 2017/01/20 21:45:26]

Done. Good point!

+    return;
+  base::trace_event::MemoryAllocatorDump* dump =
+      pmd->CreateAllocatorDump(base::StringPrintf(
+          "%s/spdy_session_pool", parent_dump_absolute_name.c_str()));
   dump->AddScalar(base::trace_event::MemoryAllocatorDump::kNameSize,
                   base::trace_event::MemoryAllocatorDump::kUnitsBytes,
                   total_size);
   dump->AddScalar(base::trace_event::MemoryAllocatorDump::kNameObjectCount,
                   base::trace_event::MemoryAllocatorDump::kUnitsObjects,
                   sessions_.size());
   dump->AddScalar("active_session_count",
                   base::trace_event::MemoryAllocatorDump::kUnitsObjects,
                   num_active_sessions);
   dump->AddScalar("buffer_size",
@@ skipping 73 matching lines @@
 
     if (idle_only && (*it)->is_active())
       continue;
 
     (*it)->CloseSessionOnError(error, description);
     DCHECK(!IsSessionAvailable(*it));
   }
 }
 
 }  // namespace net