Update mojo sdk to rev 8d45c89c30b230843c5bd6dd0693a555750946c0

third_party/mojo/src/mojo/public/cpp/bindings/string.h

Index: third_party/mojo/src/mojo/public/cpp/bindings/string.h
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/string.h b/third_party/mojo/src/mojo/public/cpp/bindings/string.h
index ba0d8fa81cef0e843829f3f3a2e499908cb5d48d..e0ed4ba1d71fc1900e9f35f9733c98163955fb5a 100644
--- a/third_party/mojo/src/mojo/public/cpp/bindings/string.h
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/string.h
@@ -13,6 +13,9 @@
 
 namespace mojo {
 
+// A UTF-8 encoded character string that can be null. Provides functions that
+// are similar to std::string, along with access to the underlying std::string
+// object.
 class String {
  public:
   typedef internal::String_Data Data_;