Add support for single sample metrics.

content/browser/renderer_host/render_process_host_impl.cc

Index: content/browser/renderer_host/render_process_host_impl.cc
diff --git a/content/browser/renderer_host/render_process_host_impl.cc b/content/browser/renderer_host/render_process_host_impl.cc
index 8bb4f2f602d1071d1e1f1b4c0d283d50ae8cb25c..cce43e6a8fa0d3f8e62cd62c1de81dcff57ec859 100644
--- a/content/browser/renderer_host/render_process_host_impl.cc
+++ b/content/browser/renderer_host/render_process_host_impl.cc
@@ -53,6 +53,7 @@
 #include "cc/base/switches.h"
 #include "cc/output/buffer_to_texture_target_map.h"
 #include "components/discardable_memory/service/discardable_shared_memory_manager.h"
+#include "components/metrics/single_value_histograms_provider.h"
 #include "components/tracing/common/tracing_switches.h"
 #include "content/browser/appcache/appcache_dispatcher_host.h"
 #include "content/browser/appcache/chrome_appcache_service.h"
@@ -1296,6 +1297,9 @@ void RenderProcessHostImpl::RegisterMojoInterfaces() {
       base::Bind(&VideoCaptureHost::Create,
                  BrowserMainLoop::GetInstance()->media_stream_manager()));
 
+  registry->AddInterface(
+      base::Bind(&metrics::SingleValueHistogramsProvider::Create));
+
   // This is to support usage of WebSockets in cases in which there is no
   // associated RenderFrame (e.g., Shared Workers).
   AddUIThreadInterface(