Store alloc history data in memory leak report protobuf

components/metrics/leak_detector/leak_detector.cc

Index: components/metrics/leak_detector/leak_detector.cc
diff --git a/components/metrics/leak_detector/leak_detector.cc b/components/metrics/leak_detector/leak_detector.cc
index d1ae9c49527eeac10467719144157374895e09d4..c41091128fbdc04b43ef78412af278958d43b92f 100644
--- a/components/metrics/leak_detector/leak_detector.cc
+++ b/components/metrics/leak_detector/leak_detector.cc
@@ -6,6 +6,8 @@
 
 #include <stdint.h>
 
+#include <algorithm>  // For std::transform

[Ilya Sherman, 2016/04/13 00:07:12]

nit: I'd omit the comment, since it's likely to drift out of date.

[Ilya Sherman, 2016/04/13 00:07:12]

... though, actually, you don't seem to use std::transform in the code.  Is this
include just not needed in the latest patch set?

[Simon Que, 2016/04/13 22:41:31]

Yes, I forgot to delete it when I no longer used it. But I'm using it in the new
patch set.

+
 #include "base/allocator/allocator_extension.h"
 #include "base/bind.h"
 #include "base/lazy_instance.h"
@@ -118,6 +120,17 @@ void GetReportsForObservers(
       memcpy(new_report->call_stack.data(), report.call_stack().data(),
              report.call_stack().size() * sizeof(report.call_stack()[0]));
     }
+
+    new_report->alloc_breakdown_history.reserve(
+        report.alloc_breakdown_history().size());

[Ilya Sherman, 2016/04/13 00:07:12]

I think you can skip this reserve() call, unless the vector size is actually
quite large.  It makes the code somewhat more complex to read, whereas I think
the performance benefit is likely to be negligible.

[Simon Que, 2016/04/13 22:41:31]

Done.

+    for (const auto& entry : report.alloc_breakdown_history()) {
+      LeakReport::AllocationBreakdown new_entry;
+      new_entry.counts_by_size.reserve(entry.counts_by_size.size());

[Ilya Sherman, 2016/04/13 00:07:12]

Ditto here, especially since you write the vector contents in a single call,
rather than adding elements one at a time.

[Simon Que, 2016/04/13 22:41:31]

Done.

+      new_entry.counts_by_size.assign(entry.counts_by_size.begin(),
+                                      entry.counts_by_size.end());
+      new_entry.count_for_call_stack = entry.count_for_call_stack;
+      new_report->alloc_breakdown_history.push_back(new_entry);
+    }
   }
 }
 
@@ -153,6 +166,11 @@ inline void StoreHookDataToTLS(HookData hook_data) {
 
 }  // namespace
 
+LeakDetector::LeakReport::AllocationBreakdown::AllocationBreakdown()
+    : count_for_call_stack(0) {}
+
+LeakDetector::LeakReport::AllocationBreakdown::~AllocationBreakdown() {}
+
 LeakDetector::LeakReport::LeakReport() {}
 
 LeakDetector::LeakReport::~LeakReport() {}