Add a benchmarking_extension API to call TCMalloc's HeapProfilerDump().

content/renderer/render_thread_impl.cc

Index: content/renderer/render_thread_impl.cc
diff --git a/content/renderer/render_thread_impl.cc b/content/renderer/render_thread_impl.cc
index 3b931b1c4b2e8c005a0d8224cc6480b7840c4047..975e13ec35cacd44864906732b0242d882a1e803 100644
--- a/content/renderer/render_thread_impl.cc
+++ b/content/renderer/render_thread_impl.cc
@@ -63,6 +63,7 @@
 #include "content/renderer/media/peer_connection_tracker.h"
 #include "content/renderer/media/video_capture_impl_manager.h"
 #include "content/renderer/media/video_capture_message_filter.h"
+#include "content/renderer/memory_benchmarking_extension.h"
 #include "content/renderer/p2p/socket_dispatcher.h"
 #include "content/renderer/plugin_channel_host.h"
 #include "content/renderer/render_process_impl.h"
@@ -357,6 +358,9 @@ void RenderThreadImpl::Init() {
   if (command_line.HasSwitch(switches::kEnableGpuBenchmarking))
       RegisterExtension(GpuBenchmarkingExtension::Get());
 
+  if (command_line.HasSwitch(switches::kEnableMemoryBenchmarking))
+    RegisterExtension(MemoryBenchmarkingExtension::Get());
+
   context_lost_cb_.reset(new GpuVDAContextLostCallback());
 
   // Note that under Linux, the media library will normally already have