Support mojo connections between unrelated peer processes.

mojo/edk/test/multiprocess_test_helper.h

Index: mojo/edk/test/multiprocess_test_helper.h
diff --git a/mojo/edk/test/multiprocess_test_helper.h b/mojo/edk/test/multiprocess_test_helper.h
index 203eb117445b89381da8feb8317953b59ba0be07..689b0ecab5bd83ad1901612a6e41dadea137c14b 100644
--- a/mojo/edk/test/multiprocess_test_helper.h
+++ b/mojo/edk/test/multiprocess_test_helper.h
@@ -27,13 +27,23 @@ class MultiprocessTestHelper {
  public:
   using HandlerCallback = base::Callback<void(ScopedMessagePipeHandle)>;
 
+  enum class LaunchType {
+    // Launch the child process as a child in the mojo system.
+    CHILD,
+
+    // Launch the child process as an unrelated peer process in the mojo system.
+    PEER,
+  };
+
   MultiprocessTestHelper();
   ~MultiprocessTestHelper();
 
   // Start a child process and run the "main" function "named" |test_child_name|
   // declared using |MOJO_MULTIPROCESS_TEST_CHILD_MAIN()| or
   // |MOJO_MULTIPROCESS_TEST_CHILD_TEST()| (below).
-  ScopedMessagePipeHandle StartChild(const std::string& test_child_name);
+  ScopedMessagePipeHandle StartChild(
+      const std::string& test_child_name,
+      LaunchType launch_type = LaunchType::CHILD);
 
   // Like |StartChild()|, but appends an extra switch (with ASCII value) to the
   // command line. (The switch must not already be present in the default
@@ -41,7 +51,8 @@ class MultiprocessTestHelper {
   ScopedMessagePipeHandle StartChildWithExtraSwitch(
       const std::string& test_child_name,
       const std::string& switch_string,
-      const std::string& switch_value);
+      const std::string& switch_value,
+      LaunchType launch_type);
 
   void set_process_error_callback(const ProcessErrorCallback& callback) {
     process_error_callback_ = callback;
@@ -69,7 +80,7 @@ class MultiprocessTestHelper {
   static int RunClientTestMain(const base::Callback<void(MojoHandle)>& main);
 
   // For use (and only valid) in the child process:
-  static std::string primordial_pipe_token;
+  static mojo::ScopedMessagePipeHandle primordial_pipe;
 
  private:
   // Valid after |StartChild()| and before |WaitForChildShutdown()|.