Add support to trace warnings in TraceBuffer.

runtime/vm/trace_buffer.h

 // Copyright (c) 2013, 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.
 
 #ifndef VM_TRACE_BUFFER_H_
 #define VM_TRACE_BUFFER_H_
 
 #include "platform/assert.h"
 #include "platform/globals.h"
 #include "vm/json_stream.h"
 
 namespace dart {
 
 class JSONStream;
+class Script;
 
 struct TraceBufferEntry {
   int64_t micros;
   char* message;
+  bool message_is_escaped;
   bool empty() const {
     return message == NULL;
   }
 };
 
 class TraceBuffer {
  public:
   static const intptr_t kDefaultCapacity = 1024;
 
   static void Init(Isolate* isolate, intptr_t capacity = kDefaultCapacity);
 
   ~TraceBuffer();
 
   void Clear();
 
   // Internally message is copied.
-  void Trace(int64_t micros, const char* message);
+  void Trace(int64_t micros, const char* msg, bool msg_is_escaped = false);
   // Internally message is copied.
-  void Trace(const char* message);
+  void Trace(const char* msg, bool msg_is_escaped = false);
   void TraceF(const char* format, ...) PRINTF_ATTRIBUTE(2, 3);
 
   void PrintToJSONStream(JSONStream* stream) const;
 
+  // Accessors for testing.
+  TraceBufferEntry* At(intptr_t i) const { return &ring_[RingIndex(i)]; }
+  intptr_t Length() const { return ring_cursor_; }
+
  private:
   TraceBuffer(Isolate* isolate, intptr_t capacity);
   void Cleanup();
-  void Fill(TraceBufferEntry* entry, int64_t micros, char* msg);
-  void AppendTrace(int64_t micros, char* message);
+  void Fill(TraceBufferEntry* entry, int64_t micros,
+            char* msg, bool msg_is_escaped = false);
+  void AppendTrace(int64_t micros, char* msg, bool msg_is_escaped = false);
 
   Isolate* isolate_;
   TraceBufferEntry* ring_;
   const intptr_t ring_capacity_;
   intptr_t ring_cursor_;
 
   intptr_t RingIndex(intptr_t i) const {
     return i % ring_capacity_;
   }
 
   DISALLOW_COPY_AND_ASSIGN(TraceBuffer);
 };
 
 
 }  // namespace dart
 
 #endif  // VM_TRACE_BUFFER_H_