Replace uses of hash_map in //base

base/trace_event/malloc_dump_provider.cc

Index: base/trace_event/malloc_dump_provider.cc
diff --git a/base/trace_event/malloc_dump_provider.cc b/base/trace_event/malloc_dump_provider.cc
index 7f2706092ee6f7aafc8283ca22e67bad13022c3c..3a4017251abf94a6d5421e1c0a90dc715c14bf14 100644
--- a/base/trace_event/malloc_dump_provider.cc
+++ b/base/trace_event/malloc_dump_provider.cc
@@ -6,6 +6,8 @@
 
 #include <stddef.h>
 
+#include <unordered_map>
+
 #include "base/allocator/allocator_extension.h"
 #include "base/allocator/allocator_shim.h"
 #include "base/allocator/features.h"
@@ -296,7 +298,7 @@ bool MallocDumpProvider::OnMemoryDump(const MemoryDumpArgs& args,
   // profiler does not see unabalanced malloc/free calls from these containers.
   {
     TraceEventMemoryOverhead overhead;
-    hash_map<AllocationContext, AllocationMetrics> metrics_by_context;
+    std::unordered_map<AllocationContext, AllocationMetrics> metrics_by_context;
     {
       AutoLock lock(allocation_register_lock_);
       if (allocation_register_) {