feat: Support async updates from the updater library. (#13)

* feat: Support async updates from the updater library.

This is the engine side of:
shorebirdtech/updater#11

I also removed passing vmpath (unused) and adjusted names
to be more consistent.

* Add DEPS change

DEPS

@@ -27,7 +27,7 @@ vars = {
   'updater_rev': '11d8c2280539f08d55c5bd0b019adbd5cfa373dc',
 
   'updater_git': 'https://github.com/shorebirdtech/updater.git',
-  'updater_rev': 'bc19f5df79005d65073debdc736f17ca6d827f89',
+  'updater_rev': '4ab78869b8e75f10450d6156c92d9ab7dc401516',
 
   # WARNING: DO NOT EDIT canvaskit_cipd_instance MANUALLY
   # See `lib/web_ui/README.md` for how to roll CanvasKit to a new version.

shell/common/shell.cc

@@ -143,7 +143,7 @@ std::unique_ptr<Shell> Shell::Create(
 // non-android targets (e.g. flutter_tester) will fail to link.
 #if FML_OS_ANDROID
   if (!vm) {
-    shorebird_report_failed_launch();
+    shorebird_report_launch_failure();
   }
 #endif
   FML_CHECK(vm) << "Must be able to initialize the VM.";

shell/platform/android/flutter_main.cc

@@ -120,34 +120,35 @@ void ConfigureShorebird(std::string android_cache_path,
     app_parameters.original_libapp_paths = c_paths.data();
     app_parameters.original_libapp_paths_size = c_paths.size();
 
-    app_parameters.vm_path = "libflutter.so";  // Unused.
-
     // shorebird_init copies from app_parameters and shorebirdYaml.
     shorebird_init(&app_parameters, shorebirdYaml.c_str());
   }
 
-  FML_LOG(INFO) << "Starting Shorebird update";
-  shorebird_update();
-
-  char* c_active_path = shorebird_active_path();
+  char* c_active_path = shorebird_next_boot_patch_path();
   if (c_active_path != NULL) {
     std::string active_path = c_active_path;
     shorebird_free_string(c_active_path);
     FML_LOG(INFO) << "Shorebird updater: active path: " << active_path;
-
-    settings.application_library_path.clear();
-    settings.application_library_path.emplace_back(active_path);
-
-    char* c_patch_number = shorebird_active_patch_number();
+    char* c_patch_number = shorebird_next_boot_patch_number();
     if (c_patch_number != NULL) {
       std::string patch_number = c_patch_number;
       shorebird_free_string(c_patch_number);
       FML_LOG(INFO) << "Shorebird updater: active patch number: "
                     << patch_number;
     }
+
+    settings.application_library_path.clear();
+    settings.application_library_path.emplace_back(active_path);
+    // Once start_update_thread is called, the next_boot_patch* functions may
+    // change their return values if the shorebird_report_launch_failed
+    // function is called.
+    shorebird_report_launch_start();
   } else {
     FML_LOG(INFO) << "Shorebird updater: no active patch.";
   }
+
+  FML_LOG(INFO) << "Starting Shorebird update";
+  shorebird_start_update_thread();
 }
 
 void FlutterMain::Init(JNIEnv* env,