Allocator cleanup: allocator_extension call directly into tcmalloc

After crrev.com/1584893002 base/ can use directly allocator.
The grand plan is to dismantle all the indirection layer such that:
 - base is the only thing that knows about allocator-specific details.
 - non-base code uses only base abstractions and stops looking
   at USE_TCMALLOC build flags.

This CL, specifically, addresses the profiling-related methods moving
the tcmalloc-specific dependencies to base and base only.
Other parts of the codebase will be cleaned up in separate CLs.

Also this CL removes a stale base/debug/OWNERS. That file makes
no sense these days as tracing has been moved to base/trace_event/.

BUG=564618

Review URL: https://codereview.chromium.org/1607303002

Cr-Commit-Position: refs/heads/master@{#371335}

2 files changed, 18 insertions, 36 deletions

diff --git a/base/allocator/allocator_extension.cc b/base/allocator/allocator_extension.cc
index 4f0b3a90..17682f8 100644
--- a/base/allocator/allocator_extension.cc
+++ b/base/allocator/allocator_extension.cc
@@ -6,34 +6,32 @@
 
 #include "base/logging.h"
 
+#if defined(USE_TCMALLOC)
+#include "third_party/tcmalloc/chromium/src/gperftools/heap-profiler.h"
+#include "third_party/tcmalloc/chromium/src/gperftools/malloc_extension.h"
+#endif
+
 namespace base {
 namespace allocator {
 
-namespace {
-ReleaseFreeMemoryFunction g_release_free_memory_function = nullptr;
-GetNumericPropertyFunction g_get_numeric_property_function = nullptr;
-}
-
 void ReleaseFreeMemory() {
-  if (g_release_free_memory_function)
-    g_release_free_memory_function();
+#if defined(USE_TCMALLOC)
+  ::MallocExtension::instance()->ReleaseFreeMemory();
+#endif
 }
 
 bool GetNumericProperty(const char* name, size_t* value) {
-  return g_get_numeric_property_function &&
-         g_get_numeric_property_function(name, value);
-}
-
-void SetReleaseFreeMemoryFunction(
-    ReleaseFreeMemoryFunction release_free_memory_function) {
-  DCHECK(!g_release_free_memory_function);
-  g_release_free_memory_function = release_free_memory_function;
+#if defined(USE_TCMALLOC)
+  return ::MallocExtension::instance()->GetNumericProperty(name, value);
+#endif
+  return false;
 }
 
-void SetGetNumericPropertyFunction(
-    GetNumericPropertyFunction get_numeric_property_function) {
-  DCHECK(!g_get_numeric_property_function);
-  g_get_numeric_property_function = get_numeric_property_function;
+bool IsHeapProfilerRunning() {
+#if defined(USE_TCMALLOC)
+  return ::IsHeapProfilerRunning();
+#endif
+  return false;
 }
 
 }  // namespace allocator
diff --git a/base/allocator/allocator_extension.h b/base/allocator/allocator_extension.h
index 3be2cea..64bfd1c 100644
--- a/base/allocator/allocator_extension.h
+++ b/base/allocator/allocator_extension.h
@@ -13,9 +13,6 @@
 namespace base {
 namespace allocator {
 
-typedef void (*ReleaseFreeMemoryFunction)();
-typedef bool (*GetNumericPropertyFunction)(const char* name, size_t* value);
-
 // Request that the allocator release any free memory it knows about to the
 // system.
 BASE_EXPORT void ReleaseFreeMemory();
@@ -26,20 +23,7 @@ BASE_EXPORT void ReleaseFreeMemory();
 // |name| or |value| cannot be NULL
 BASE_EXPORT bool GetNumericProperty(const char* name, size_t* value);
 
-// These settings allow specifying a callback used to implement the allocator
-// extension functions.  These are optional, but if set they must only be set
-// once.  These will typically called in an allocator-specific initialization
-// routine.
-//
-// No threading promises are made.  The caller is responsible for making sure
-// these pointers are set before any other threads attempt to call the above
-// functions.
-
-BASE_EXPORT void SetReleaseFreeMemoryFunction(
-    ReleaseFreeMemoryFunction release_free_memory_function);
-
-BASE_EXPORT void SetGetNumericPropertyFunction(
-    GetNumericPropertyFunction get_numeric_property_function);
+BASE_EXPORT bool IsHeapProfilerRunning();
 
 }  // namespace allocator
 }  // namespace base