An API for setting the tag for Flutter log messages on Android (#3335)

Fixes https://github.com/flutter/flutter/issues/7226

common/settings.h

@@ -30,6 +30,7 @@ struct Settings {
   std::string application_library_path;
   std::string temp_directory_path;
   std::vector<std::string> dart_flags;
+  std::string log_tag = "flutter";
 
   static const Settings& Get();
   static void Set(const Settings& settings);

lib/ui/dart_runtime_hooks.cc

@@ -11,6 +11,7 @@
 #include "dart/runtime/bin/embedded_dart_io.h"
 #include "dart/runtime/include/dart_api.h"
 #include "dart/runtime/include/dart_tools_api.h"
+#include "flutter/common/settings.h"
 #include "lib/ftl/build_config.h"
 #include "lib/ftl/logging.h"
 #include "lib/tonic/converter/dart_converter.h"
@@ -152,7 +153,8 @@ void Logger_PrintString(Dart_NativeArguments args) {
 #if defined(OS_ANDROID)
     // In addition to writing to the stdout, write to the logcat so that the
     // message is discoverable when running on an unrooted device.
-    __android_log_print(ANDROID_LOG_INFO, "flutter", "%.*s", (int)length,
+    const char* tag = Settings::Get().log_tag.c_str();
+    __android_log_print(ANDROID_LOG_INFO, tag, "%.*s", (int)length,
                         chars);
 #elif __APPLE__
     syslog(1 /* LOG_ALERT */, "%.*s", (int)length, chars);

shell/common/shell.cc

@@ -189,6 +189,11 @@ void Shell::InitStandalone(std::string icu_data_path,
       settings.dart_flags.push_back(*it);
   }
 
+  if (command_line.HasSwitch(FlagForSwitch(Switch::LogTag))) {
+    settings.log_tag = command_line.GetSwitchValueASCII(
+        FlagForSwitch(Switch::LogTag));
+  }
+
   blink::Settings::Set(settings);
 
   Init();

shell/common/switches.h

@@ -55,6 +55,7 @@ DEF_SWITCH(EndlessTraceBuffer,
            "indefinitely however.")
 DEF_SWITCH(FLX, "flx", "Specify the the FLX path.")
 DEF_SWITCH(Help, "help", "Display this help text.")
+DEF_SWITCH(LogTag, "log-tag", "Tag associated with log messages.")
 DEF_SWITCH(MainDartFile, "dart-main", "The path to the main Dart file.")
 DEF_SWITCH(NonInteractive,
            "non-interactive",

shell/platform/android/io/flutter/view/FlutterMain.java

@@ -83,6 +83,7 @@ public class FlutterMain {
     private static boolean sInitialized = false;
     private static ResourceExtractor sResourceExtractor;
     private static boolean sIsPrecompiled;
+    private static Settings sSettings;
 
     private static final class ImmutableSetBuilder<T> {
         static <T> ImmutableSetBuilder<T> newInstance() {
@@ -111,10 +112,34 @@ public class FlutterMain {
         }
     }
 
+    public static class Settings {
+        private String logTag;
+
+        public String getLogTag() {
+            return logTag;
+        }
+
+        /**
+         * Set the tag associated with Flutter app log messages.
+         */
+        public void setLogTag(String tag) {
+            logTag = tag;
+        }
+    }
+
     /**
      * Starts initialization of the native system.
      */
     public static void startInitialization(Context applicationContext) {
+        startInitialization(applicationContext, new Settings());
+    }
+
+    /**
+     * Starts initialization of the native system.
+     */
+    public static void startInitialization(Context applicationContext, Settings settings) {
+        sSettings = settings;
+
         long initStartTimestampMillis = SystemClock.uptimeMillis();
         initConfig(applicationContext);
         initJavaUtils(applicationContext);
@@ -157,6 +182,10 @@ public class FlutterMain {
                     PathUtils.getCacheDirectory(applicationContext));
             }
 
+            if (sSettings.getLogTag() != null) {
+                shellArgs.add("--log-tag=" + sSettings.getLogTag());
+            }
+
             nativeInit(applicationContext, shellArgs.toArray(new String[0]));
 
             sInitialized = true;