[HttpCache] Store some memcache info to memory dumps for debugging

net/http/http_cache.cc

Index: net/http/http_cache.cc
diff --git a/net/http/http_cache.cc b/net/http/http_cache.cc
index 1dc390a474c3abcc21e95539ed56ef75fb9dda16..bf423eccf48f79822767518d49828fc0e94c11e3 100644
--- a/net/http/http_cache.cc
+++ b/net/http/http_cache.cc
@@ -130,9 +130,9 @@ struct HttpCache::PendingOp {
 
   // Returns the estimate of dynamically allocated memory in bytes.
   size_t EstimateMemoryUsage() const {
-    // |disk_entry| is tracked in |backend|.
-    return base::trace_event::EstimateMemoryUsage(backend) +
-           base::trace_event::EstimateMemoryUsage(writer) +
+    // Note that backend isn't counted because it doesn't provide an EMU
+    // function.

[xunjieli, 2017/03/27 18:29:06]

If a backend is in PendingOp, does that mean the backend doesn't have much
allocations because it is being created? 

[jkarlin, 2017/03/28 15:09:45]

Yep.

+    return base::trace_event::EstimateMemoryUsage(writer) +
            base::trace_event::EstimateMemoryUsage(pending_queue);
   }
 
@@ -512,16 +512,17 @@ void HttpCache::DumpMemoryStats(base::trace_event::ProcessMemoryDump* pmd,
                                 const std::string& parent_absolute_name) const {
   // Skip tracking members like |clock_| and |backend_factory_| because they
   // don't allocate.
-  base::trace_event::MemoryAllocatorDump* dump =
-      pmd->CreateAllocatorDump(parent_absolute_name + "/http_cache");
-  dump->AddScalar(
-      base::trace_event::MemoryAllocatorDump::kNameSize,
-      base::trace_event::MemoryAllocatorDump::kUnitsBytes,
-      base::trace_event::EstimateMemoryUsage(disk_cache_) +
-          base::trace_event::EstimateMemoryUsage(active_entries_) +
-          base::trace_event::EstimateMemoryUsage(doomed_entries_) +
-          base::trace_event::EstimateMemoryUsage(playback_cache_map_) +
-          base::trace_event::EstimateMemoryUsage(pending_ops_));
+  std::string name = parent_absolute_name + "/http_cache";
+  base::trace_event::MemoryAllocatorDump* dump = pmd->CreateAllocatorDump(name);
+  size_t size = base::trace_event::EstimateMemoryUsage(active_entries_) +
+                base::trace_event::EstimateMemoryUsage(doomed_entries_) +
+                base::trace_event::EstimateMemoryUsage(playback_cache_map_) +
+                base::trace_event::EstimateMemoryUsage(pending_ops_);
+  if (disk_cache_)
+    size += disk_cache_->DumpMemoryStats(pmd, name);
+
+  dump->AddScalar(base::trace_event::MemoryAllocatorDump::kNameSize,
+                  base::trace_event::MemoryAllocatorDump::kUnitsBytes, size);
 }
 
 //-----------------------------------------------------------------------------