Remove tcmalloc when not being used. Restore shim on Windows.

base/allocator/win_allocator.cc

Index: base/allocator/win_allocator.cc
diff --git a/base/allocator/win_allocator.cc b/base/allocator/win_allocator.cc
index ee451f546101c008c0b081f4c880790c20027bd6..279606c26e4a675f314fd3e3a8eab39a3bc74ed8 100644
--- a/base/allocator/win_allocator.cc
+++ b/base/allocator/win_allocator.cc
@@ -6,27 +6,33 @@
 
 extern "C" {
 
+const size_t kWindowsPageSize = 4096;
+size_t kMaxWindowsAllocation =
+    std::numeric_limits<int>::max() - kWindowsPageSize;
 HANDLE win_heap;
 
-bool win_heap_init(bool use_lfh) {
-  win_heap = HeapCreate(0, 0, 0);
+bool win_heap_init() {
+  win_heap = static_cast<HANDLE>(GetProcessHeap());
   if (win_heap == NULL)
     return false;
 
-  if (use_lfh) {
-    ULONG enable_lfh = 2;
-    HeapSetInformation(win_heap, HeapCompatibilityInformation,
-                       &enable_lfh, sizeof(enable_lfh));
-    // NOTE: Setting LFH may fail.  Vista already has it enabled.
-    //       And under the debugger, it won't use LFH.  So we
-    //       ignore any errors.
-  }
+  ULONG enable_lfh = 2;
+  // NOTE: Setting LFH may fail.  Vista already has it enabled.
+  //       And under the debugger, it won't use LFH.  So we
+  //       ignore any errors.
+  HeapSetInformation(win_heap, HeapCompatibilityInformation, &enable_lfh,
+                     sizeof(enable_lfh));
 
+  // In Debug, _mt_init() performs an allocation before _cinit is called to
+  // initalize C data, so manually initialize kMaxWindowsAllocation here.
+  kMaxWindowsAllocation = std::numeric_limits<int>::max() - kWindowsPageSize;
   return true;
 }
 
 void* win_heap_malloc(size_t size) {
-  return HeapAlloc(win_heap, 0, size);
+  if (size < kMaxWindowsAllocation)
+    return HeapAlloc(win_heap, 0, size);
+  return NULL;
 }
 
 void win_heap_free(void* size) {
@@ -40,7 +46,9 @@ void* win_heap_realloc(void* ptr, size_t size) {
     win_heap_free(ptr);
     return NULL;
   }
-  return HeapReAlloc(win_heap, 0, ptr, size);
+  if (size < kMaxWindowsAllocation)
+    return HeapReAlloc(win_heap, 0, ptr, size);
+  return NULL;
 }
 
 size_t win_heap_msize(void* ptr) {