[Telemetry] Add capability for values to reference external files.

tools/telemetry/telemetry/value/__init__.py

Index: tools/telemetry/telemetry/value/__init__.py
diff --git a/tools/telemetry/telemetry/value/__init__.py b/tools/telemetry/telemetry/value/__init__.py
index 8bba418e09af16f4afa2f7005597da594a1e3066..8d03d78eb218e6924ff3e596a19c56b3047386ff 100644
--- a/tools/telemetry/telemetry/value/__init__.py
+++ b/tools/telemetry/telemetry/value/__init__.py
@@ -42,7 +42,7 @@ SUMMARY_RESULT_OUTPUT_CONTEXT = 'summary-result-output-context'
 class Value(object):
   """An abstract value produced by a telemetry page test.
   """
-  def __init__(self, page, name, units, important, description):
+  def __init__(self, page, name, units, important, description, paths):
     """A generic Value object.
 
     Args:
@@ -56,12 +56,17 @@ class Value(object):
           by default in downstream UIs.
       description: A string explaining in human-understandable terms what this
           value represents.
+      paths: A list of paths corresponding to files associated with this value.

[nednguyen, 2014/09/08 18:45:24]

What are paths? Are they strings, or are they instances of some classes? In
addition, what does it mean if some paths are relative? i.e: which file location
does ./foo.txt refers too? Do paths need to exist?

It seems to me that having a Path class like your previous patch that answers
these questions and raise corresponding exceptions in case of invalid values is
better the strings representation.

     """
     self.page = page
     self.name = name
     self.units = units
     self.important = important
     self.description = description
+    if paths is None:
+      self.paths = []
+    else:
+      self.paths = paths
 
   def IsMergableWith(self, that):
     return (self.units == that.units and
@@ -187,6 +192,11 @@ class Value(object):
     if self.page:
       d['page_id'] = self.page.id

[nduca, 2014/09/08 18:53:02]

How about

   ""Returns file handle... or none."""
   def GetAssociatedFileHandle(self):
     return None

 
+    if self.paths:
+      # Assigning IDs to paths is a serialization detail, so we defer updating
+      # this to an ID until we actually intend on serializing this value.
+      d['paths'] = self.paths
+
     return d
 
   def AsDictWithoutBaseClassEntries(self):