Track SimpleCache memory usage in net/ MemoryDumpProvider

net/disk_cache/simple/simple_backend_impl.cc

Index: net/disk_cache/simple/simple_backend_impl.cc
diff --git a/net/disk_cache/simple/simple_backend_impl.cc b/net/disk_cache/simple/simple_backend_impl.cc
index e5645e357ebd44aecac4b580e3fb88444f7dc7b9..e81877c9017bef6324ef7883b2daa1357ca74456 100644
--- a/net/disk_cache/simple/simple_backend_impl.cc
+++ b/net/disk_cache/simple/simple_backend_impl.cc
@@ -30,6 +30,7 @@
 #include "base/threading/sequenced_worker_pool.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/time/time.h"
+#include "base/trace_event/memory_usage_estimator.h"
 #include "net/base/net_errors.h"
 #include "net/disk_cache/cache_util.h"
 #include "net/disk_cache/simple/simple_entry_format.h"
@@ -204,6 +205,13 @@ void RecordIndexLoad(net::CacheType cache_type,
 
 }  // namespace
 
+// Static function which is called by base::trace_event::EstimateMemoryUsage()
+// to estimate the memory of SimpleEntryImpl* type.
+// This needs to be in disk_cache namespace.
+size_t EstimateMemoryUsage(const SimpleEntryImpl* const& entry_impl) {

[jkarlin, 2017/02/24 18:38:09]

Have you verified that this actually gets called? I don't see it defined in the
header.

I think we need more tests to verify that everything is actually being counted.

[xunjieli, 2017/02/24 18:42:17]

I verified manually that this is called. (build chrome locally and get a trace
from chrome://tracing). The unit test (backend_unittest.cc) also enters this
code, but I am not sure what's the best way to write a stricter test expectation
(rather than using LT(0, EMU()).

+  return sizeof(SimpleEntryImpl) + entry_impl->EstimateMemoryUsage();
+}
+
 class SimpleBackendImpl::ActiveEntryProxy
     : public SimpleEntryImpl::ActiveEntryProxy {
  public:
@@ -552,6 +560,13 @@ void SimpleBackendImpl::OnExternalCacheHit(const std::string& key) {
   index_->UseIfExists(simple_util::GetEntryHashKey(key));
 }
 
+size_t SimpleBackendImpl::EstimateMemoryUsage() const {
+  // TODO(xunjieli): crbug.com/669108. Track |entries_pending_doom_| once
+  // base::Closure is suppported in memory_usage_estimator.h.
+  return base::trace_event::EstimateMemoryUsage(index_) +
+         base::trace_event::EstimateMemoryUsage(active_entries_);
+}
+
 void SimpleBackendImpl::InitializeIndex(const CompletionCallback& callback,
                                         const DiskStatResult& result) {
   if (result.net_error == net::OK) {