Mojo EDK: Introduce MojoQueryHandleSignalsState API

mojo/edk/test/mojo_test_base.h

Index: mojo/edk/test/mojo_test_base.h
diff --git a/mojo/edk/test/mojo_test_base.h b/mojo/edk/test/mojo_test_base.h
index fa5b64ced93a1d497017a8fa6d551ffe1de4eac0..35e2c2b12f9986b85a99daade269382eb713789c 100644
--- a/mojo/edk/test/mojo_test_base.h
+++ b/mojo/edk/test/mojo_test_base.h
@@ -30,8 +30,6 @@ class MojoTestBase : public testing::Test {
   ~MojoTestBase() override;
 
   using LaunchType = MultiprocessTestHelper::LaunchType;
-
- protected:
   using HandlerCallback = base::Callback<void(ScopedMessagePipeHandle)>;
 
   class ClientController {
@@ -152,6 +150,14 @@ class MojoTestBase : public testing::Test {
   // Reads data from a data pipe.
   static std::string ReadData(MojoHandle consumer, size_t size);
 
+  // Queries the signals state of |handle|.
+  static MojoHandleSignalsState GetSignalsState(MojoHandle handle);
+
+  // Helper to block the calling thread waiting for signals to be raised.
+  static MojoResult WaitForSignals(MojoHandle handle,
+                                   MojoHandleSignals signals,
+                                   MojoHandleSignalsState* state = nullptr);
+
   void set_launch_type(LaunchType launch_type) { launch_type_ = launch_type; }
 
  private: