[telemetry] Timeline model cleanups

tools/telemetry/telemetry/core/timeline/bounds.py

Index: tools/telemetry/telemetry/core/timeline/bounds.py
diff --git a/tools/telemetry/telemetry/core/timeline/bounds.py b/tools/telemetry/telemetry/core/timeline/bounds.py
new file mode 100644
index 0000000000000000000000000000000000000000..9bbe1badb3fdba08ca1b09cbf384b60ffa10e4fe
--- /dev/null
+++ b/tools/telemetry/telemetry/core/timeline/bounds.py
@@ -0,0 +1,71 @@
+# Copyright (c) 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 Bounds(object):
+  """Represents a min-max bounds."""
+  def __init__(self):
+    self.is_empty_ = True
+    self.min_ = None
+    self.max_ = None
+
+  @property
+  def is_empty(self):
+    return self.is_empty_
+
+  @property
+  def min(self):
+    if self.is_empty_:
+      return None
+    return self.min_
+
+  @property
+  def max(self):
+    if self.is_empty_:
+      return None
+    return self.max_
+
+  @property
+  def bounds(self):
+    if self.is_empty_:
+      return None
+    return self.max_ - self.min_
+
+  @property
+  def center(self):
+    return (self.min_ + self.max_) * 0.5
+
+
+  def Reset(self):
+    self.is_empty_ = True
+    self.min_ = None
+    self.max_ = None
+
+  def AddBounds(self, bounds):
+    if bounds.isEmpty:
+      return
+    self.AddValue(bounds.min_)
+    self.AddValue(bounds.max_)
+
+  def AddValue(self, value):
+    if self.is_empty_:
+      self.max_ = value
+      self.min_ = value
+      self.is_empty_ = False
+      return
+
+    self.max_ = max(self.max_, value)
+    self.min_ = min(self.min_, value)
+
+  @staticmethod
+  def CompareByMinTimes(a, b):
+    if not a.is_empty and not b.is_empty:
+      return a.min_ - b.min_
+
+    if a.is_empty and not b.is_empty:
+      return -1
+
+    if not a.is_empty and b.is_empty:
+      return 1
+
+    return 0