Add applaunchd gRPC API wrapper

Changes:
- Add applaunchd gRPC API wrapper in applauncher directory, clients
  can include AppLauncherClient.h to use it.
- To facilitate generating protobuf and gRPC code with protoc,
  switch from CMake to meson for building.  While the code
  generation can be done in CMake, it is a lot more straightforward
  with meson, and if use of this library continues meson will be
  easier to maintain.

Known issues:
- The behavior of the client implementation here with respect to the
  server side (i.e. applaunchd) going away is currently robust, but
  could stand improvement with some further investigation.  As the
  code stands, starting applications works when applaunchd becomes
  available again, but the streaming status RPC that is tied to
  window activation in the homescreen does not reconnect, and there
  seem to be some things that need to be resolved with respect to
  Qt object connection expiry to do so.  If the Qt demos continue to
  be used in a significant fashion, this may be worth picking up.

Bug-AGL: SPEC-4559

Signed-off-by: Scott Murray <scott.murray@konsulko.com>
Change-Id: I5cb480d4ce4d1cb944ebfd4114fb305f09f28ea3

1 files changed, 50 insertions, 0 deletions

diff --git a/applauncher/protos/applauncher.proto b/applauncher/protos/applauncher.proto
new file mode 100644
index 0000000..0b8e0fc
--- /dev/null
+++ b/applauncher/protos/applauncher.proto
@@ -0,0 +1,50 @@
+syntax = "proto3";
+
+package automotivegradelinux;
+
+service AppLauncher {
+  rpc StartApplication(StartRequest) returns (StartResponse) {}
+  rpc ListApplications(ListRequest) returns (ListResponse) {}
+  rpc GetStatusEvents(StatusRequest) returns (stream StatusResponse) {}
+}
+
+message StartRequest {
+  string id = 1;
+}
+
+message StartResponse {
+  bool status = 1;
+  string message = 2;
+}
+
+message ListRequest {
+}
+
+message ListResponse {
+  repeated AppInfo apps = 1;
+}
+
+message AppInfo {
+  string id = 1;
+  string name = 2;
+  string icon_path = 3;
+}
+
+message StatusRequest {
+}
+
+message AppStatus {
+  string id = 1;
+  string status = 2;
+}
+
+// Future-proofing for e.g. potentially signaling a list refresh
+message LauncherStatus {
+}
+
+message StatusResponse {
+  oneof status {
+    AppStatus app = 1;
+    LauncherStatus launcher = 2;
+  }
+}