Mojo: Suppress validation error logging in some tests

mojo/public/cpp/bindings/lib/validation_errors.h

Index: mojo/public/cpp/bindings/lib/validation_errors.h
diff --git a/mojo/public/cpp/bindings/lib/validation_errors.h b/mojo/public/cpp/bindings/lib/validation_errors.h
index 7636e391dad4414dfff7659a04e75c12e9dd1ff4..122418d9e3d2eee11b5a5d86c3f42a5f802e67d6 100644
--- a/mojo/public/cpp/bindings/lib/validation_errors.h
+++ b/mojo/public/cpp/bindings/lib/validation_errors.h
@@ -89,6 +89,20 @@ MOJO_CPP_BINDINGS_EXPORT void ReportValidationErrorForMessage(
     ValidationError error,
     const char* description = nullptr);
 
+// This class may be used by tests to suppress validation error logging. This is
+// not thread-safe and must only be instantiated on the main thread with no
+// other threads using Mojo bindings at the time of construction or destruction.
+class MOJO_CPP_BINDINGS_EXPORT ScopedSuppressValidationErrorLoggingForTests {
+ public:
+  ScopedSuppressValidationErrorLoggingForTests();
+  ~ScopedSuppressValidationErrorLoggingForTests();
+
+ private:
+  const bool was_suppressed_;
+
+  DISALLOW_COPY_AND_ASSIGN(ScopedSuppressValidationErrorLoggingForTests);
+};
+
 // Only used by validation tests and when there is only one thread doing message
 // validation.
 class MOJO_CPP_BINDINGS_EXPORT ValidationErrorObserverForTesting {