Route calls to tcmalloc MallocExtension through allocator agnostic interface

base/allocator/allocator_shim.cc

Index: base/allocator/allocator_shim.cc
diff --git a/base/allocator/allocator_shim.cc b/base/allocator/allocator_shim.cc
index d61a9a47ff573d183ee372e6a01b740c2bebfc59..63639b2c95d7125c04d7d7f8110590f172287b39 100644
--- a/base/allocator/allocator_shim.cc
+++ b/base/allocator/allocator_shim.cc
@@ -5,6 +5,7 @@
 #include "base/allocator/allocator_shim.h"
 
 #include <config.h>
+#include "base/allocator/allocator_extension_thunks.h"
 #include "base/profiler/alternate_timer.h"
 #include "base/sysinfo.h"
 
@@ -229,6 +230,14 @@ extern "C" intptr_t _get_heap_handle() {
   return 0;
 }
 
+static void get_stats_thunk(char* buffer, int buffer_length) {
+  MallocExtension::instance()->GetStats(buffer, buffer_length);
+}
+
+static void release_free_memory_thunk() {
+  MallocExtension::instance()->ReleaseFreeMemory();
+}
+
 // The CRT heap initialization stub.
 extern "C" int _heap_init() {
 #ifdef ENABLE_DYNAMIC_ALLOCATOR_SWITCHING
@@ -273,6 +282,10 @@ extern "C" int _heap_init() {
         tcmalloc::ThreadCache::GetBytesAllocatedOnCurrentThread);
   }
 
+  base::allocator::thunks::SetGetStatsFunction(get_stats_thunk);
+  base::allocator::thunks::SetReleaseFreeMemoryFunction(
+      release_free_memory_thunk);
+
   return 1;
 }