[mojo] Fix some lint errors

mojo/edk/system/core.h

Index: mojo/edk/system/core.h
diff --git a/mojo/edk/system/core.h b/mojo/edk/system/core.h
index e32e2d2a8e6715f969dc2053112cfc9999cf5358..21b44b1a69f45ff0505e36b10220b3e57de42aeb 100644
--- a/mojo/edk/system/core.h
+++ b/mojo/edk/system/core.h
@@ -6,6 +6,7 @@
 #define MOJO_EDK_SYSTEM_CORE_H_
 
 #include <memory>
+#include <string>
 #include <vector>
 
 #include "base/callback.h"
@@ -39,7 +40,7 @@ namespace edk {
 // are thread-safe.
 class MOJO_SYSTEM_IMPL_EXPORT Core {
  public:
-  explicit Core();
+  Core();
   virtual ~Core();
 
   // Called exactly once, shortly after construction, and before any other
@@ -278,7 +279,7 @@ class MOJO_SYSTEM_IMPL_EXPORT Core {
                               const MojoHandleSignals* signals,
                               uint32_t num_handles,
                               MojoDeadline deadline,
-                              uint32_t *result_index,
+                              uint32_t* result_index,
                               HandleSignalsState* signals_states);
 
   // Used to pass ownership of our NodeController over to the IO thread in the