Replace GetAllErrorCodesForUma calls with UMA_HISTOGRAM_SPARSE_SLOWLY.

content/browser/download/download_resource_handler.cc

Index: content/browser/download/download_resource_handler.cc
diff --git a/content/browser/download/download_resource_handler.cc b/content/browser/download/download_resource_handler.cc
index 045c0f0e17e90979a55dd42e1662903a220a6046..646dc854d78d100145bdcea40fa847ca22cd51c9 100644
--- a/content/browser/download/download_resource_handler.cc
+++ b/content/browser/download/download_resource_handler.cc
@@ -10,6 +10,7 @@
 #include "base/logging.h"
 #include "base/message_loop/message_loop_proxy.h"
 #include "base/metrics/histogram.h"

[Alexei Svitkine (slow), 2015/05/15 20:38:27]

Ditto.

[davidben, 2015/05/15 20:41:01]

Done.

+#include "base/metrics/sparse_histogram.h"
 #include "base/strings/stringprintf.h"
 #include "content/browser/byte_stream.h"
 #include "content/browser/download/download_create_info.h"
@@ -453,9 +454,8 @@ void DownloadResourceHandler::OnResponseCompleted(
   // If the error mapped to something unknown, record it so that
   // we can drill down.
   if (reason == DOWNLOAD_INTERRUPT_REASON_NETWORK_FAILED) {
-    UMA_HISTOGRAM_CUSTOM_ENUMERATION("Download.MapErrorNetworkFailed",
-                                     std::abs(status.error()),
-                                     net::GetAllErrorCodesForUma());
+    UMA_HISTOGRAM_SPARSE_SLOWLY("Download.MapErrorNetworkFailed",
+                                std::abs(status.error()));
   }
 
   stream_writer_.reset();  // We no longer need the stream.