Convert string16 to base::string16 in content.

content/common/sandbox_win.cc

Index: content/common/sandbox_win.cc
diff --git a/content/common/sandbox_win.cc b/content/common/sandbox_win.cc
index f5c86f7d2cb23c6a981703e5c43d3d22a4026ab8..cf13a1d00e12f3b33f6d82c17e3bb9652c5dc4cd 100644
--- a/content/common/sandbox_win.cc
+++ b/content/common/sandbox_win.cc
@@ -217,7 +217,7 @@ void AddGenericDllEvictionPolicy(sandbox::TargetPolicy* policy) {
 }
 
 // Returns the object path prepended with the current logon session.
-string16 PrependWindowsSessionPath(const char16* object) {
+base::string16 PrependWindowsSessionPath(const char16* object) {
   // Cache this because it can't change after process creation.
   static uintptr_t s_session_id = 0;
   if (s_session_id == 0) {
@@ -514,7 +514,7 @@ void SetJobLevel(const CommandLine& cmd_line,
 // Just have to figure out what needs to be warmed up first.
 void AddBaseHandleClosePolicy(sandbox::TargetPolicy* policy) {
   // TODO(cpu): Add back the BaseNamedObjects policy.
-  string16 object_path = PrependWindowsSessionPath(
+  base::string16 object_path = PrependWindowsSessionPath(
       L"\\BaseNamedObjects\\windows_shell_global_counters");
   policy->AddKernelObjectToClose(L"Section", object_path.data());
 }