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

media/tools/layout_tests/trend_graph.py

Index: media/tools/layout_tests/trend_graph.py
diff --git a/media/tools/layout_tests/trend_graph.py b/media/tools/layout_tests/trend_graph.py
index c39fff88343d3e8e347d454a74465fc5b11a2dbf..9261562028eecaa4f5480205f04d5ce26cdeb41b 100644
--- a/media/tools/layout_tests/trend_graph.py
+++ b/media/tools/layout_tests/trend_graph.py
@@ -45,6 +45,11 @@ class TrendGraph(object):
           as values for graph annotation.
     """
     joined_str = ''
+    # For a date format in GViz, month is shifted (e.g., '2008,1,1' means

[dennis_jeffrey, 2011/09/01 00:29:13]

Maybe pick a slightly different example than "2008,1,1", since it's not clear
which of the two 1's is the month (though I suspect it's the first '1').  How
about this: '2008,2,1', which I think is 'March 1, 2008', right?

[imasaki1, 2011/09/01 03:08:23]

Done.

+    # Feb. 1st, 2008).
+    str_list = datetime_string.split(',')

[dennis_jeffrey, 2011/09/01 00:29:13]

Just to clarify: if we have 'Jan. 1, 2008', does that mean the inputted string
will be '2008,0,1'?

Or is it the reverse: the inputted string for 'Jan. 1, 2008' will be '2008,1,1',
and that's why we need to shift the month to instead be '2008,0,1'?

[imasaki1, 2011/09/01 03:08:23]

The input string for 'Jan. 1, 2008' is  '2008,0,1'.

[dennis_jeffrey, 2011/09/01 16:56:42]

Ok, if that is true, then won't line 51 below subtract 1 from the input '0' to
make it '-1' in the case of January ('2008,0,1' will become '2008,-1,1')?  That
seems weird to me.

[imasaki1, 2011/09/03 19:35:13]

Sorry I was not clear.

Input string ranges from (2008,1,1) to (2008,12,31) in the case of year 2008.
The output to gviz ranging from (2008,0,1) to (2008,11,31).

+    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,