Remove lineprocessor sample.

This sample used to demonstrate the usage of the DebuggerAgent. The latter
has been removed, so this sample has no point anymore.

R=ulan@chromium.org

Review URL: https://codereview.chromium.org/754043002

Cr-Commit-Position: refs/heads/master@{#25488}

samples/samples.gyp

@@ -67,11 +67,5 @@
         'process.cc',
       ],
     },
-    {
-      'target_name': 'lineprocessor',
-      'sources': [
-        'lineprocessor.cc',
-      ],
-    }
   ],
 }