Cut the spam in the dart handler log printouts.

mojo/dart/embedder/builtin_natives.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
 #include "base/files/file_enumerator.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "crypto/random.h"
 #include "dart/runtime/include/dart_api.h"
 #include "mojo/dart/embedder/builtin.h"
 #include "mojo/dart/embedder/mojo_natives.h"
 
+#if defined(OS_ANDROID)
+#include <android/log.h>
+#endif
+
 namespace mojo {
 namespace dart {
 
 // Lists the native functions implementing basic functionality in
 // the Mojo embedder dart, such as printing, and file I/O.
 #define BUILTIN_NATIVE_LIST(V)                                                 \
   V(Crypto_GetRandomBytes, 1)                                                  \
   V(Logger_PrintString, 1)                                                     \
   V(Builtin_ReadSync, 1)                                                       \
   V(Builtin_EnumerateFiles, 1)                                                 \
@@ skipping 43 matching lines @@
 // Implementation of native functions which are used for some
 // test/debug functionality in standalone dart mode.
 void Logger_PrintString(Dart_NativeArguments args) {
   intptr_t length = 0;
   uint8_t* chars = nullptr;
   Dart_Handle str = Dart_GetNativeArgument(args, 0);
   Dart_Handle result = Dart_StringToUTF8(str, &chars, &length);
   if (Dart_IsError(result)) {
     Dart_PropagateError(result);
   } else {
-  // TODO(dart): Hook up to developer console (if/when that's a thing).
-#if defined(OS_ANDROID)
-    std::string message(reinterpret_cast<char*>(chars), length);
-    LOG(INFO) << "CONSOLE: " << message;
-#else
+    // TODO(dart): Hook up to developer console (if/when that's a thing).
     // Uses fwrite to support printing NUL bytes.
     fwrite(chars, 1, length, stdout);
     fputs("\n", stdout);
+#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. Use the
+    // "chromium" tag to match native printouts produced by base LOG macros, so
+    // that the same rule will pick them up in scripts that stream relevant
+    // logcat output to host terminal.
+    __android_log_print(ANDROID_LOG_INFO, "chromium", "%.*s", length, chars);
 #endif
   }
   fflush(stdout);
 }
 
 void Builtin_ReadSync(Dart_NativeArguments args) {
   intptr_t chars_length = 0;
   uint8_t* chars = nullptr;
   Dart_Handle file_uri = Dart_GetNativeArgument(args, 0);
   if (!Dart_IsString(file_uri)) {
@@ skipping 223 matching lines @@
     Dart_Handle error = Dart_NewStringFromCString(
         "Failed to allocate storage.");
     Dart_ThrowException(error);
   }
   Dart_ListSetAsBytes(result, 0, buffer.get(), count);
   Dart_SetReturnValue(args, result);
 }
 
 }  // namespace bin
 }  // namespace dart