Don't try to access an Isolate when don't have one yet.

content/child/content_child_helpers.cc

Index: content/child/content_child_helpers.cc
diff --git a/content/child/content_child_helpers.cc b/content/child/content_child_helpers.cc
index bafd28f6ee9e8932cb965d879dbeeef60962a101..d6d62922d0229842a50a68434ba0e46aea951df1 100644
--- a/content/child/content_child_helpers.cc
+++ b/content/child/content_child_helpers.cc
@@ -29,7 +29,9 @@ size_t GetMemoryUsageKB() {
   v8::HeapStatistics stat;
   // TODO(svenpanne) The call below doesn't take web workers into account, this
   // has to be done manually by iterating over all Isolates involved.
-  v8::Isolate::GetCurrent()->GetHeapStatistics(&stat);
+  v8::Isolate* isolate = v8::Isolate::GetCurrent();
+  if (isolate)
+    isolate->GetHeapStatistics(&stat);
   return mem_usage + (static_cast<uint64_t>(stat.total_heap_size()) >> 10);
 }
 #elif defined(OS_MACOSX)