Make URLRequestContext a MemoryDumpProvider (Abandoned)

net/base/sdch_manager.cc

Index: net/base/sdch_manager.cc
diff --git a/net/base/sdch_manager.cc b/net/base/sdch_manager.cc
index e57d73cfb24ab437fff321a170dbc42a5c7e067f..4b23fd3a1bcb930a7500411c06e9bb74cd250aa0 100644
--- a/net/base/sdch_manager.cc
+++ b/net/base/sdch_manager.cc
@@ -13,7 +13,10 @@
 #include "base/metrics/histogram_macros.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
+#include "base/strings/stringprintf.h"
 #include "base/time/default_clock.h"
+#include "base/trace_event/memory_allocator_dump.h"
+#include "base/trace_event/process_memory_dump.h"
 #include "base/values.h"
 #include "crypto/sha2.h"
 #include "net/base/parse_number.h"
@@ -324,6 +327,32 @@ void SdchManager::RemoveObserver(SdchObserver* observer) {
   observers_.RemoveObserver(observer);
 }
 
+void SdchManager::DumpMemoryStats(
+    base::trace_event::ProcessMemoryDump* pmd) const {
+  std::string name = base::StringPrintf("net/sdch_manager_%p", this);
+  base::trace_event::MemoryAllocatorDump* dictionary_dump =
+      pmd->GetAllocatorDump(name);
+  if (dictionary_dump)

[eroman, 2016/11/29 22:22:50]

What are the circumstances when this would be reached?

Is the thinking that we may have a shared SdchManager between
URLRequestContexts? And hence when we enumerate through the URLRequestContexts
we skip duplicate logging here?

Please add a comment on intent. Should it add an ownership edge like in the
other location with shared state?

[xunjieli, 2016/11/30 16:02:03]

Done.

URLRequestContexts currently don't share a SdchManager, though they in theory
can. I have added a comment here and an ownership edge.

+    return;
+  size_t total_size = 0;
+  size_t total_count = 0;
+  for (const auto& dictionary : dictionaries_) {
+    total_size += dictionary.second->data.text().size();
+    ++total_count;

[eroman, 2016/11/29 22:22:50]

maybe just dictionaries_.size() outside of loop?

[xunjieli, 2016/11/30 16:02:03]

Done.

+  }
+  if (total_count == 0)
+    return;
+  dictionary_dump = pmd->CreateAllocatorDump(name);
+  dictionary_dump->AddScalar(
+      base::trace_event::MemoryAllocatorDump::kNameSize,
+      base::trace_event::MemoryAllocatorDump::kUnitsBytes, total_size);
+
+  // Use the existing column name so as not to add a new column.

[eroman, 2016/11/29 22:22:50]

I am not sure what this comment means regarding "existing" column? Is this about
the UI presentation or "count" being a common name used somewhere else?

[xunjieli, 2016/11/30 16:02:03]

Done. Sorry, there is a constant
(base::trace_event::MemoryAllocatorDump::kObjectsCount) that I can used here. I
have removed the confusing comment.

+  dictionary_dump->AddScalar(
+      "count", base::trace_event::MemoryAllocatorDump::kUnitsObjects,
+      total_count);
+}
+
 SdchProblemCode SdchManager::AddSdchDictionary(
     const std::string& dictionary_text,
     const GURL& dictionary_url,