Add JS heap snapshotting functionality to Telemetry (part 2)

tools/telemetry/telemetry/core/heap/live_heap_object.py

Index: tools/telemetry/telemetry/core/heap/live_heap_object.py
diff --git a/tools/telemetry/telemetry/core/heap/live_heap_object.py b/tools/telemetry/telemetry/core/heap/live_heap_object.py
new file mode 100644
index 0000000000000000000000000000000000000000..c8be3df69bd61d76e7bf9d6daff48536f8db1596
--- /dev/null
+++ b/tools/telemetry/telemetry/core/heap/live_heap_object.py
@@ -0,0 +1,57 @@
+# Copyright 2013 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.
+
+class LiveHeapObject(object):
+  """Data structure for representing an object in the heap snapshot.
+
+  Attributes:
+    object_id: int, identifier for the object.
+    type_string: str, describes the type of the node.
+    class_name: str, describes the class of the JavaScript object
+        represented by this LiveHeapObject.
+    edges_to: [RetainingEdge], edges whose end point this LiveHeapObject is.
+    edges_from: [RetainingEdge], edges whose start point this LiveHeapObject is.
+    string: str, for string LiveHeapObjects, contains the string the
+        LiveHeapObject represents. Empty string for LiveHeapObjects which are
+        not strings.
+    name: str, how to refer to this LiveHeapObject.
+  """
+
+  def __init__(self, object_id, type_string, class_name):
+    """Initializes the LiveHeapObject object.
+
+    Args:
+      object_id: int, identifier for the LiveHeapObject.
+      type_string: str, the type of the node.
+      class_name: str, the class of the object this LiveHeapObject represents.
+    """
+    self.object_id = object_id
+    self.type_string = type_string
+    self.class_name = class_name
+    self.edges_to = []
+    self.edges_from = []
+    self.string = ''
+    self.name = ''
+
+  def AddEdgeTo(self, edge):
+    """Associates an Edge with the LiveHeapObject (the end point).
+
+    Args:
+      edge: Edge, an edge whose end point this LiveHeapObject is.
+    """
+    self.edges_to.append(edge)
+
+  def AddEdgeFrom(self, edge):
+    """Associates an Edge with the LiveHeapObject (the start point).
+
+    Args:
+      edge: Edge, an edge whose start point this LiveHeapObject is.
+    """
+    self.edges_from.append(edge)
+
+  def __str__(self):
+    prefix = 'LiveHeapObject(' + str(self.object_id) + ' '
+    if self.type_string == 'object':
+      return prefix + self.class_name + ')'
+    return prefix + self.type_string + ')'