Replace uses of hash_map in //base

base/trace_event/process_memory_dump_unittest.cc

Index: base/trace_event/process_memory_dump_unittest.cc
diff --git a/base/trace_event/process_memory_dump_unittest.cc b/base/trace_event/process_memory_dump_unittest.cc
index 571774a10ca2224e469e447902be2e0b5618953b..4ee6508190c14048f3a0899b4e24917e65bf52eb 100644
--- a/base/trace_event/process_memory_dump_unittest.cc
+++ b/base/trace_event/process_memory_dump_unittest.cc
@@ -90,7 +90,7 @@ TEST(ProcessMemoryDumpTest, Clear) {
 
 TEST(ProcessMemoryDumpTest, TakeAllDumpsFrom) {
   std::unique_ptr<TracedValue> traced_value(new TracedValue);
-  hash_map<AllocationContext, AllocationMetrics> metrics_by_context;
+  std::unordered_map<AllocationContext, AllocationMetrics> metrics_by_context;
   metrics_by_context[AllocationContext()] = { 1, 1 };
   TraceEventMemoryOverhead overhead;