[tracing] Add a memory dump provider for DOM storage

content/browser/dom_storage/dom_storage_context_impl.cc

Index: content/browser/dom_storage/dom_storage_context_impl.cc
diff --git a/content/browser/dom_storage/dom_storage_context_impl.cc b/content/browser/dom_storage/dom_storage_context_impl.cc
index 7fee39c34abf0647fe6e9c329bafdf54c76fe190..cfeafa5ef69ed4024843aad00f46529a8be5d052 100644
--- a/content/browser/dom_storage/dom_storage_context_impl.cc
+++ b/content/browser/dom_storage/dom_storage_context_impl.cc
@@ -14,6 +14,8 @@
 #include "base/guid.h"
 #include "base/location.h"
 #include "base/time/time.h"
+#include "base/trace_event/memory_dump_manager.h"
+#include "base/trace_event/process_memory_dump.h"
 #include "content/browser/dom_storage/dom_storage_area.h"
 #include "content/browser/dom_storage/dom_storage_database.h"
 #include "content/browser/dom_storage/dom_storage_namespace.h"
@@ -50,6 +52,13 @@ DOMStorageContextImpl::DOMStorageContextImpl(
   // namespace ids at one since zero is reserved for the
   // kLocalStorageNamespaceId.
   session_id_sequence_.GetNext();
+
+  // Registering dump provider is safe even outside the task runner.
+  base::trace_event::MemoryDumpManager::GetInstance()
+      ->RegisterDumpProviderWithSequencedTaskRunner(
+          this, "DOMStorage", task_runner_->GetSequencedTaskRunner(
+                                  DOMStorageTaskRunner::PRIMARY_SEQUENCE),
+          base::trace_event::MemoryDumpProvider::Options());
 }
 
 DOMStorageContextImpl::~DOMStorageContextImpl() {

[michaeln, 2016/04/26 22:56:25]

can you add a DCHECK(is_shutdown_) here to test our desirement about that having
happened and run some tryjobs, i bet there are cases where that is not true :(

@@ -179,6 +188,9 @@ void DOMStorageContextImpl::Shutdown() {
   for (; it != namespaces_.end(); ++it)
     it->second->Shutdown();
 
+  base::trace_event::MemoryDumpManager::GetInstance()->UnregisterDumpProvider(
+      this);
+
   if (localstorage_directory_.empty() && !session_storage_database_.get())
     return;
 
@@ -357,6 +369,17 @@ void DOMStorageContextImpl::StartScavengingUnusedSessionStorage() {
   }
 }
 
+bool DOMStorageContextImpl::OnMemoryDump(
+    const base::trace_event::MemoryDumpArgs& args,
+    base::trace_event::ProcessMemoryDump* pmd) {
+  for (const auto& it : namespaces_) {
+    it.second->OnMemoryDump(pmd);
+  }
+  if (session_storage_database_)
+    session_storage_database_->OnMemoryDump(pmd);
+  return true;
+}
+
 void DOMStorageContextImpl::FindUnusedNamespaces() {
   DCHECK(session_storage_database_.get());
   if (scavenging_started_)