Enable memory profiler when TC_MALLOC is enabled for

content/app/content_main_runner.cc

Index: content/app/content_main_runner.cc
===================================================================
--- content/app/content_main_runner.cc	(revision 148994)
+++ content/app/content_main_runner.cc	(working copy)
@@ -4,6 +4,8 @@
 
 #include "content/public/app/content_main_runner.h"
 
+#include <stdlib.h>
+
 #include "base/allocator/allocator_extension.h"
 #include "base/at_exit.h"
 #include "base/command_line.h"
@@ -17,6 +19,7 @@
 #include "base/metrics/stats_table.h"
 #include "base/path_service.h"
 #include "base/process_util.h"
+#include "base/profiler/alternate_timer.h"
 #include "base/stringprintf.h"
 #include "base/string_number_conversions.h"
 #include "content/browser/browser_main.h"
@@ -450,6 +453,17 @@
     // On windows, we've already set these thunks up in _heap_init()
     base::allocator::SetGetStatsFunction(GetStatsThunk);
     base::allocator::SetReleaseFreeMemoryFunction(ReleaseFreeMemoryThunk);
+
+    // Provide optional hook for monitoring allocation quantities on a
+    // per-thread basis.  Only set the hook if the environment indicates this
+    // needs to be enabled.
+    const char* profiling = getenv(tracked_objects::kAlternateProfilerTime);
+    tracked_objects::TimeSourceType time_source_type =
+        tracked_objects::TIME_SOURCE_TYPE_TCMALLOC;
+    if (profiling && atoi(profiling) == time_source_type) {
+      tracked_objects::SetAlternateTimeSource(
+          MallocExtension::GetBytesAllocatedOnCurrentThread, time_source_type);
+    }
 #endif
 
     // On Android,