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

tools/telemetry/telemetry/value/trace.py

+# Copyright 2014 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.
+
+import tempfile
+
+from telemetry import value as value_module
+from telemetry.util import file_handle
+
+
+class TraceValue(value_module.Value):
+  def __init__(self, page, name, timeline_data, important=False,
+               description=None):
+    super(TraceValue, self).__init__(page, name, None, important, description)
+
+    tf = tempfile.NamedTemporaryFile()
+    self._file_handle = file_handle.FileHandle.FromTempFile(tf)

[nduca, 2014/09/16 20:56:24]

swap line 17 and 18

+    timeline_data.Serialize(tf)

[nduca, 2014/09/16 20:56:24]

tf = ... timelineD_ata.Serialize(tf)


tf2 = NamedTemporaryFile()

import telemetry.web_components
from trace_viewer.build import trace2html

trace2html.WriteHTMLForTracesToFile([tf.name], tf2)
this._file_handle = file_handle.BlahBlah(tf2)

+
+  def GetAssociatedFileHandle(self):
+    return self._file_handle
+
+  def __repr__(self):
+    if self.page:
+      page_name = self.page.url
+    else:
+      page_name = None
+    return 'TraceValue(%s, %s)' % (page_name, self.name)
+
+  def GetBuildbotDataType(self, output_context):
+    return None
+
+  def GetBuildbotValue(self):
+    return None
+
+  def GetChartAndTraceNameForPerPageResult(self):
+    return None
+
+  def GetRepresentativeNumber(self):
+    return None
+
+  def GetRepresentativeString(self):
+    return None
+
+  @staticmethod
+  def GetJSONTypeName():
+    return 'trace'
+
+  @classmethod
+  def MergeLikeValuesFromSamePage(cls, values):

[nednguyen, 2014/09/16 16:15:04]

This should explode if these values are not the same.

[nduca, 2014/09/16 20:56:24]

this is fine, for now. There is an even better solution here but its follow up:
the trace file should be html. Then once we have that, we can make a
MultiTraceViewer.

# TODO(eakuenfer): Implement a MultiTraceValue

+    assert len(values) > 0
+    return values[0]
+
+  @classmethod
+  def MergeLikeValuesFromDifferentPages(cls, values,
+                                        group_by_name_suffix=False):
+    return None
+
+  def AsDict(self):
+    d = super(TraceValue, self).AsDict()
+    d['file_id'] = self._file_handle.id
+
+    return d