[tracing] Add native allocation tracing mode.

base/trace_event/heap_profiler_heap_dump_writer.cc

Index: base/trace_event/heap_profiler_heap_dump_writer.cc
diff --git a/base/trace_event/heap_profiler_heap_dump_writer.cc b/base/trace_event/heap_profiler_heap_dump_writer.cc
index b94c31246b9d347d42c285d04878c586ed7f9163..da68cd8840d09b58c9f726cc0fd038b87475dbdc 100644
--- a/base/trace_event/heap_profiler_heap_dump_writer.cc
+++ b/base/trace_event/heap_profiler_heap_dump_writer.cc
@@ -66,14 +66,14 @@ bool operator<(const Bucket& lhs, const Bucket& rhs) {
 // returned list will have |backtrace_cursor| advanced or
 // |is_broken_down_by_type_name| set depending on the property to group by.
 std::vector<Bucket> GetSubbuckets(const Bucket& bucket, BreakDownMode breakBy) {
-  base::hash_map<const char*, Bucket> breakdown;
+  base::hash_map<StackFrame, Bucket> breakdown;
 
   if (breakBy == BreakDownMode::kByBacktrace) {
     for (const auto& context_and_size : bucket.bytes_by_context) {
       const Backtrace& backtrace = context_and_size.first->backtrace;
-      const char* const* begin = std::begin(backtrace.frames);
-      const char* const* end = std::end(backtrace.frames);
-      const char* const* cursor = begin + bucket.backtrace_cursor;
+      const StackFrame* begin = std::begin(backtrace.frames);

[Primiano Tucci (use gerrit), 2016/04/01 15:56:28]

if StackFrame is "const char*", I think
const char* const* begin
should become:
StackFrame const* begin

same below

[Dmitry Skiba, 2016/04/04 22:38:34]

Actually, 'const StackFrame*' and 'StackFrame const*' are equivalent here, and
both produce 'void const* const*'. ('backtrace' is const&, so assigning
'backtrace.frames' to anything other than  'void const* const*' wouldn't
compile.)

+      const StackFrame* end = std::end(backtrace.frames);
+      const StackFrame* cursor = begin + bucket.backtrace_cursor;
 
       // The backtrace in the context is padded with null pointers, but these
       // should not be considered for breakdown. Adjust end to point past the
@@ -189,13 +189,13 @@ bool HeapDumpWriter::AddEntryForBucket(const Bucket& bucket) {
 
   const AllocationContext* context = bucket.bytes_by_context.front().first;
 
-  const char* const* backtrace_begin = std::begin(context->backtrace.frames);
-  const char* const* backtrace_end = backtrace_begin + bucket.backtrace_cursor;
+  const StackFrame* backtrace_begin = std::begin(context->backtrace.frames);
+  const StackFrame* backtrace_end = backtrace_begin + bucket.backtrace_cursor;
   DCHECK_LE(bucket.backtrace_cursor, arraysize(context->backtrace.frames));
 
   Entry entry;
-  entry.stack_frame_id =
-      stack_frame_deduplicator_->Insert(backtrace_begin, backtrace_end);
+  entry.stack_frame_id = stack_frame_deduplicator_->Insert(
+      context->backtrace.frame_type, backtrace_begin, backtrace_end);
 
   // Deduplicate the type name, or use ID -1 if type name is not set.
   entry.type_id = bucket.is_broken_down_by_type_name
@@ -236,8 +236,11 @@ const std::set<Entry>& HeapDumpWriter::Summarize(
   for (const auto& context_and_size : bytes_by_context) {
     const AllocationContext* context = &context_and_size.first;
     const size_t size = context_and_size.second;
-    root_bucket.bytes_by_context.push_back(std::make_pair(context, size));
-    root_bucket.size += size;
+    if (size != 0) {

[Primiano Tucci (use gerrit), 2016/04/01 15:56:28]

uh do we see any zero allocations?

[Dmitry Skiba, 2016/04/04 22:38:34]

Yup. Maybe we need to ignore them earlier, in MallocDumpProvider?

+      // GetSubbuckets() expects non-zero allocations
+      root_bucket.bytes_by_context.push_back(std::make_pair(context, size));
+      root_bucket.size += size;
+    }
   }
 
   AddEntryForBucket(root_bucket);