[Tracing] Enable heap dumps with both type info and backtraces

base/trace_event/heap_profiler_allocation_context.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef BASE_TRACE_EVENT_HEAP_PROFILER_ALLOCATION_CONTEXT_H_
 #define BASE_TRACE_EVENT_HEAP_PROFILER_ALLOCATION_CONTEXT_H_
 
 #include <stdint.h>
 
 #include "base/base_export.h"
@@ skipping 64 matching lines @@
 
 bool BASE_EXPORT operator==(const AllocationContext& lhs,
                             const AllocationContext& rhs);
 
 }  // namespace trace_event
 }  // namespace base
 
 namespace BASE_HASH_NAMESPACE {
 
 template <>
-struct hash<base::trace_event::Backtrace> {
+struct BASE_EXPORT hash<base::trace_event::Backtrace> {

[Primiano Tucci (use gerrit), 2015/12/09 17:03:59]

just doublechecking: does this need to be exported because you need it in the
unittests (which in component builds are a different link unit?)

[Ruud van Asseldonk, 2015/12/09 20:58:04]

content/child also uses it now. The |AllocationContext| hash, that is.
|Backtrace| doesn’t strictly need to be exported, but it was bad style because
it is in the headers, so putting this in a hash map outside of base would
compile perfectly fine and then fail to link. I should have exported this in the
first place, but I forgot. (And you missed it when reviewing :)

   size_t operator()(const base::trace_event::Backtrace& backtrace) const;
 };
 
 template <>
-struct hash<base::trace_event::AllocationContext> {
+struct BASE_EXPORT hash<base::trace_event::AllocationContext> {
   size_t operator()(const base::trace_event::AllocationContext& context) const;
 };
 
 }  // BASE_HASH_NAMESPACE
 
 #endif  // BASE_TRACE_EVENT_HEAP_PROFILER_ALLOCATION_CONTEXT_H_