Hook up logging between tts service library and Chrome

R=dmazzoni@chromium.org, rni@google.com

Change-Id: Id876d13aa592850ea5a771cfe66da80aafbe6d0e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2230932
Commit-Queue: David Tseng <dtseng@chromium.org>
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#776241}

chromeos/services/tts/BUILD.gn

@@ -42,6 +42,7 @@ generate_library_loader("libchrometts") {
   bundled_header = "\"chromeos/services/tts/chrome_tts.h\""
 
   functions = [
+    "GoogleTtsSetLogger",
     "GoogleTtsInit",
     "GoogleTtsShutdown",
     "GoogleTtsInstallVoice",

chromeos/services/tts/chrome_tts.h

@@ -8,6 +8,8 @@
 #include <cstddef>
 #include <cstdint>
 
+void GoogleTtsSetLogger(void (*logger_func)(int severity, const char* message));
+
 bool GoogleTtsInit(const char* pipeline_path, const char* path_prefix);
 
 void GoogleTtsShutdown();

chromeos/services/tts/tts_service.cc

@@ -12,6 +12,23 @@
 namespace chromeos {
 namespace tts {
 
+// Simple helper to bridge logging in the shared library to Chrome's logging.
+void HandleLibraryLogging(int severity, const char* message) {
+  switch (severity) {
+    case logging::LOG_INFO:
+      // Suppressed.
+      break;
+    case logging::LOG_WARNING:
+      LOG(WARNING) << message;
+      break;
+    case logging::LOG_ERROR:
+      LOG(ERROR) << message;
+      break;
+    default:
+      break;
+  }
+}
+
 // TtsService is mostly glue code that adapts the TtsStream interface into a
 // form needed by libchrometts.so. As is convention with shared objects, the
 // lifetime of all arguments passed to the library is scoped to the function.
@@ -24,6 +41,8 @@ TtsService::TtsService(mojo::PendingReceiver<mojom::TtsService> receiver)
   bool loaded = libchrometts_.Load(kLibchromettsPath);
   if (!loaded)
     LOG(ERROR) << "Unable to load libchrometts.so: " << dlerror();
+  else
+    libchrometts_.GoogleTtsSetLogger(HandleLibraryLogging);
 }
 
 TtsService::~TtsService() = default;