Add a new GetInstance() method for singleton classes used in chrome/browser files.

chrome/browser/renderer_host/render_sandbox_host_linux.cc

Index: chrome/browser/renderer_host/render_sandbox_host_linux.cc
diff --git a/chrome/browser/renderer_host/render_sandbox_host_linux.cc b/chrome/browser/renderer_host/render_sandbox_host_linux.cc
index 92105b441447df7b12ff50abf6e3f9a2a874a14a..51fa55b488443e6341858b528a9ad39b19caa360 100644
--- a/chrome/browser/renderer_host/render_sandbox_host_linux.cc
+++ b/chrome/browser/renderer_host/render_sandbox_host_linux.cc
@@ -23,6 +23,7 @@
 #include "base/process_util.h"
 #include "base/scoped_ptr.h"
 #include "base/shared_memory.h"
+#include "base/singleton.h"
 #include "base/string_number_conversions.h"
 #include "base/string_util.h"
 #include "base/unix_domain_socket_posix.h"
@@ -643,6 +644,11 @@ RenderSandboxHostLinux::RenderSandboxHostLinux()
       pid_(0) {
 }
 
+// static
+RenderSandboxHostLinux* RenderSandboxHostLinux::GetInstance() {
+  return Singleton<RenderSandboxHostLinux>::get();
+}
+
 void RenderSandboxHostLinux::Init(const std::string& sandbox_path) {
   DCHECK(!initialized_);
   initialized_ = true;