Add breakpoints and single-stepping to Observatory.

runtime/vm/debugger.h

 // Copyright (c) 2012, 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_DEBUGGER_H_
 #define VM_DEBUGGER_H_
 
 #include "include/dart_debugger_api.h"
 
 #include "vm/object.h"
@@ skipping 332 matching lines @@
   void Shutdown();
 
   void NotifyCompilation(const Function& func);
 
   RawFunction* ResolveFunction(const Library& library,
                                const String& class_name,
                                const String& function_name);
 
   // Set breakpoint at closest location to function entry.
   SourceBreakpoint* SetBreakpointAtEntry(const Function& target_function);
+
+  // TODO(turnidge): script_url may no longer be specific enough.
   SourceBreakpoint* SetBreakpointAtLine(const String& script_url,
                                         intptr_t line_number);
   void OneTimeBreakAtEntry(const Function& target_function);
 
   void RemoveBreakpoint(intptr_t bp_id);
   SourceBreakpoint* GetBreakpointById(intptr_t id);
 
   void SetStepOver();
   void SetSingleStep();
   void SetStepOut();
@@ skipping 185 matching lines @@
 
   friend class Isolate;
   friend class SourceBreakpoint;
   DISALLOW_COPY_AND_ASSIGN(Debugger);
 };
 
 
 }  // namespace dart
 
 #endif  // VM_DEBUGGER_H_