mac: Hook up allocator shim during app startup.

base/process/memory_mac.mm

Index: base/process/memory_mac.mm
diff --git a/base/process/memory_mac.mm b/base/process/memory_mac.mm
index 155004dc0a43e257a4918d79b9e9b7aca4a96182..4b5a3ce9c8cb60834b8ab52ab594fa4585481585 100644
--- a/base/process/memory_mac.mm
+++ b/base/process/memory_mac.mm
@@ -5,10 +5,18 @@
 #include "base/process/memory.h"
 
 #include "base/allocator/allocator_interception_mac.h"
+#include "base/allocator/allocator_shim.h"
+#include "base/allocator/features.h"
 #include "build/build_config.h"
 
 namespace base {
 
+namespace {
+void oom_killer_new() {
+  TerminateBecauseOutOfMemory(0);
+}
+}  // namespace
+
 void EnableTerminationOnHeapCorruption() {
 #if !ARCH_CPU_64_BITS
   DLOG(WARNING) << "EnableTerminationOnHeapCorruption only works on 64-bit";
@@ -24,6 +32,17 @@ bool UncheckedCalloc(size_t num_items, size_t size, void** result) {
 }
 
 void EnableTerminationOnOutOfMemory() {
+  // Step 1: Enable OOM killer on C++ failures.
+  std::set_new_handler(oom_killer_new);
+
+// Step 2: Enable OOM killer on C-malloc failures for the default zone (if we
+// have a shim).
+#if BUILDFLAG(USE_EXPERIMENTAL_ALLOCATOR_SHIM)
+  allocator::SetCallNewHandlerOnMallocFailure(true);
+#endif
+
+  // Step 3: Enable OOM killer on all other malloc zones (or just "all" without
+  // "other" if shim is disabled).
   allocator::InterceptAllocationsMac();
 }