Support piping log data over the service protocol

sdk/lib/developer/developer.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /// Interact with developer tools such as the debugger and inspector.
 ///
 /// The dart:developer library is _unstable_ and its API might change slightly
 /// as a result of developer feedback. This library is platform dependent and
 /// therefore it has implementations for both dart2js and the Dart VM. Both are
 /// under development and may not support all operations yet.
 ///
 library dart.developer;
 
+import 'dart:async';
 import 'dart:convert';
 
 part 'profiler.dart';
 
 /// If [when] is true, stop the program as if a breakpoint were hit at the
 /// following statement.
-/// 
+///
 /// Returns the value of [when]. Some debuggers may
 /// display [msg].
-/// 
+///
 /// NOTE: When invoked, the isolate will not return until a debugger
 /// continues execution. When running in the Dart VM the behaviour is the same
 /// regardless of whether or not a debugger is connected. When compiled to
 /// JavaScript, this uses the "debugger" statement, and behaves exactly as
 /// that does.
 external bool debugger({bool when: true, String msg});
 
 /// Send a reference to [object] to any attached debuggers.
-/// 
+///
 /// Debuggers may open an inspector on the object. Returns the argument.
 external inspect(object);
+
+/// Emit a log event.
+/// [sequenceNumber] is a monotonically increasing sequence number.

[rmacnak, 2015/07/17 00:17:56]

What happens if this is called with the same sequence number repeatedly? In
particular, independent event sources seem likely to choose conflicting sequence
numbers.

[Cutch, 2015/07/17 00:50:13]

Note that all of these fields and their restrictions are dictated by the logging
package.

With my UI right now, it makes no difference. In the future, we may sort log
items based on their sequence number. If a program can't keep their sequence
numbers straight they may have a problem. 

+/// [millisececondsSinceEpoch] is a timestamp.
+/// [level] is the severity level (value between 0 and 2000 inclusive).

[rmacnak, 2015/07/17 00:17:56]

Are high or low values more severe?

[Cutch, 2015/07/17 00:50:13]

Note that all of these fields and their restrictions are dictated by the logging
package.

High values are more severe.

+/// [name] is the name of the source of the log message.
+/// [message] is the log message.
+/// [zone] (optional) the zone where the log was emitted
+/// [error] (optional) an error object associated with this log event.
+/// [stackTrace] (optional) a stack trace associated with this log event.
+external log(int sequenceNumber,
+             int millisecondsSinceEpoch,
+             int level,
+             String name,
+             String message,
+             [Zone zone,
+              Object error,
+              StackTrace stackTrace]);
+
+/// Emit a log event for a a [LogRecord] from the [logging] package.
+void logOnRecord(dynamic logRecord) {
+  log(logRecord.sequenceNumber,
+      logRecord.time.millisecondsSinceEpoch,
+      logRecord.level.value,
+      logRecord.loggerName,
+      logRecord.message,
+      null,
+      logRecord.error,
+      logRecord.stackTrace);
+}