Web MIDI: add dynamic MidiManager instantiation support for Linux

media/midi/midi_manager_unittest.cc

Index: media/midi/midi_manager_unittest.cc
diff --git a/media/midi/midi_manager_unittest.cc b/media/midi/midi_manager_unittest.cc
index 6b680c35abc417abe7589a898e4d1cd15ce03f6d..c1d30dc4e734917b7b0ca6b8292f8a1357f437b8 100644
--- a/media/midi/midi_manager_unittest.cc
+++ b/media/midi/midi_manager_unittest.cc
@@ -18,6 +18,7 @@
 #include "base/run_loop.h"
 #include "base/system_monitor/system_monitor.h"
 #include "build/build_config.h"
+#include "media/midi/midi_service.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace midi {
@@ -111,6 +112,7 @@ class MidiManagerTest : public ::testing::Test {
  public:
   MidiManagerTest()
       : manager_(new FakeMidiManager),
+        service_(new MidiService(base::WrapUnique(manager_))),
         message_loop_(new base::MessageLoop) {}
   ~MidiManagerTest() override {
     manager_->Shutdown();
@@ -163,7 +165,8 @@ class MidiManagerTest : public ::testing::Test {
   }
 
  protected:
-  std::unique_ptr<FakeMidiManager> manager_;
+  FakeMidiManager* manager_;  // Owned by |service_|.
+  std::unique_ptr<MidiService> service_;
 
  private:
   std::unique_ptr<base::MessageLoop> message_loop_;