Add README file and parametrize result directory in layout test analzyer tool.

media/tools/layout_tests/trend_graph.py

 #!/usr/bin/python
 # Copyright (c) 2011 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 fileinput
 import os
 import sys
 
 
@@ skipping 21 matching lines @@
     """Initialize this object with the location of trend graph."""
     self._location = location
 
   def Update(self, datetime_string, data_map):
     """Update trend graphs using |datetime_string| and |data_map|.
 
     There are two kinds of graphs to be updated (one is for numbers and the
     other is for passing rates).
 
     Args:
-        datetime_string: a datetime string (e.g., '2008,1,1,13,45,00)'
+        datetime_string: a datetime string delimited by ','
+          (e.g., '2008,1,1,13,45,00)'. For example, in the case of the year
+          2008, this ranges from '2008,1,1,0,0,00' to '2008,12,31,23,59,99'.
         data_map: a dictionary containing 'whole', 'skip' , 'nonskip',
           'passingrate' as its keys and (number, tile, text) string tuples
           as values for graph annotation.
     """
     joined_str = ''
+    # For a date format in GViz, month is shifted (e.g., '2008,2,1' means
+    # March 1, 2008). So, the input parameter |datetime_string| (before this
+    # conversion) must be shifted in order to show the date properly on GViz.
+    # After the below conversion, for example, in the case of the year 2008,
+    # |datetime_string| ranges from '2008,0,1,0,0,00' to '2008,11,31,23,59,99'.
+    str_list = datetime_string.split(',')
+    str_list[1] = str(int(str_list[1])-1) # month
+    datetime_string = ','.join(str_list)
     for key in ['whole', 'skip', 'nonskip']:
       joined_str += ','.join(data_map[key]) + ','
     new_line_for_numbers = '         [new Date(%s),%s],\n' % (datetime_string,
                                                               joined_str)
     new_line_for_numbers += '         %s\n' % (
         LINE_INSERT_POINT_FOR_NUMBERS)
     self._ReplaceLine(LINE_INSERT_POINT_FOR_NUMBERS, new_line_for_numbers)
 
     joined_str = '%s,%s,%s' % (
         data_map['passingrate'][0], data_map['nonskip'][1],
@@ skipping 11 matching lines @@
     Args:
         search_exp: search expression to find a line to be replaced.
         replace_line: the new line.
     """
     replaced = False
     for line in fileinput.input(self._location, inplace=1):
       if search_exp in line:
         replaced = True
         line = replace_line
       sys.stdout.write(line)