Add trace to the caller of QuotaManager::GetAvailableSpace

storage/browser/quota/quota_manager_proxy.cc

Index: storage/browser/quota/quota_manager_proxy.cc
diff --git a/storage/browser/quota/quota_manager_proxy.cc b/storage/browser/quota/quota_manager_proxy.cc
index c8ccefc1ad230051422591af0953856a990e86c9..eed11c94e5a622a7bed1c8d8a1caf603f1d39cdc 100644
--- a/storage/browser/quota/quota_manager_proxy.cc
+++ b/storage/browser/quota/quota_manager_proxy.cc
@@ -10,6 +10,7 @@
 #include "base/single_thread_task_runner.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/task_runner_util.h"
+#include "base/trace_event/trace_event.h"
 
 namespace storage {
 
@@ -137,6 +138,10 @@ void QuotaManagerProxy::GetUsageAndQuota(
     DidGetUsageAndQuota(original_task_runner, callback, kQuotaErrorAbort, 0, 0);
     return;
   }
+
+  // crbug.com/349708
+  TRACE_EVENT0("io", "QuotaManagerProxy::GetUsageAndQuota");
+
   manager_->GetUsageAndQuota(
       origin, type,
       base::Bind(&DidGetUsageAndQuota,