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..b7f2ec62e88eef306e2a446850823da669a2707c 100644
--- a/base/trace_event/malloc_dump_provider.cc
+++ b/base/trace_event/malloc_dump_provider.cc
@@ -296,7 +296,7 @@ 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;

[Łukasz Anforowicz, 2017/04/24 18:46:10]

IWYU: #include <unordered_map> ?  (I don't see such include here nor in
malloc_dump_provider.h)

     {
       AutoLock lock(allocation_register_lock_);
       if (allocation_register_) {