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

media/tools/layout_tests/README

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+Layout test analyzer script.
+
+* Prerequisite:
+
+This script requires PySVN (http://pysvn.tigris.org/) to be installed on the
+machine.
+
+* How to execute
+
+python layouttest_analyzer.py (Please run with '-h' for available command-line
+                               options)

[dennis_jeffrey, 2011/08/31 17:49:40]

(optional) You may want to also give a full example invocation using some of the
commonly-used flags.

[imasaki1, 2011/08/31 19:08:19]

Done.

+
+* Directory structure

[dennis_jeffrey, 2011/08/31 17:49:40]

The description of the directory structure seems to be missing.

[imasaki1, 2011/08/31 19:08:19]

Done.

+
+Design overview:
+
+* Execution overflow overview.

[dennis_jeffrey, 2011/08/31 17:49:40]

I'm not sure what you mean by 'overflow' here; could we remove that word?

[imasaki1, 2011/08/31 19:08:19]

Done.

+
+First, using PySVN, the script collects layout test of interest
+(specified in command-line parameter and testnames/*.csv file) from
+Webkit SVN repository as well as test description. Then, it gets the
+the latest test expectation file and does the simple parsing. The

[dennis_jeffrey, 2011/08/31 17:49:40]

remove 'the' at the start of this line (it's duplicated from the previous line)

[imasaki1, 2011/08/31 19:08:19]

Done.

+parsed test expectation is joined with the layout tests using test name
+as its join key. The tests are classified into 'whole', 'skip',
+'nonskip' test groups. 'Whole' contains all tests, 'skip' contains
+tests are skipped as specified in the test expectation file, 'nonskip'

[dennis_jeffrey, 2011/08/31 17:49:40]

'tests are' --> 'tests that are'

[imasaki1, 2011/08/31 19:08:19]

Done.

+tests are in the test expectation file and not skipped (these are tests
+that needs attention).

[dennis_jeffrey, 2011/08/31 17:49:40]

'needs' --> 'need'

[imasaki1, 2011/08/31 19:08:19]

Done.

+
+Next, the script reads the previous latest analyzer results, then,
+compares it with current results for each test group ('whole', 'skip',
+and 'nonskip'). It also looks into the SVN test expectation history
+diff for the time period for the test names of interest.
+
+Thirdly, all obtained information sent out to a email list specified
+in the parameters in pretty HTML format.
+
+Lastly, the trend graph is updated using the current results.

[dennis_jeffrey, 2011/08/31 17:49:40]

(optional) For lines 19-38, it might be a little easier to read if we list each
step in a numbered list (as compared to paragraphs of text).

[imasaki1, 2011/08/31 19:08:19]

Done.

+
+* Components
+
+** LayoutTests:
+
+A class to store test names in layout tests. The test names (including
+regular expression patterns) are read from a CSV file and used for
+getting layout test names from Webkit SVN as well as test description.
+
+** TestExpectations:
+
+A class to model the content of test expectation file for analysis.
+The raw test expectation file can be found in
+|DEFAULT_TEST_EXPECTATION_LOCATION|.  It is necessary to parse this
+file and store meaningful information for the analysis (joining with
+existing layout tests using a test name).  Instance variable
+|all_test_expectation_info| is used.  A test name such as
+'media/video-source-type.html' is used for the key to store
+information. However, a test name can appear multiple times in the
+test expectation file. So, the map should keep all the occurrence
+information. For example, the current test expectation file has the
+following two entries: 
+
+BUGWK58587 LINUX DEBUG GPU : media/video-zoom.html = IMAGE 
+BUGCR86714 MAC GPU : media/video-zoom.html = CRASH IMAGE 
+
+In this case, all_test_expectation_info['media/video-zoom.html'] will
+have a list with two elements, each of which is the map of the test
+expectation information.
+
+** TestExpectationsHistory:
+
+A class to represent history of the test expectation file. The history
+is obtained by calling PySVN.log()/diff() APIs using the specified time
+period.
+
+** TrendGraph: 
+
+A class to manage trend graph which is using Google Visualization
+  APIs. Google Visualization API
+  (http://code.google.com/apis/chart/interactive/docs/gallery/annotatedtimeline.html)
+  is used to present the historical analyzer result. Currently, data
+  is directly written to JavaScript file using file in-place
+  replacement for simplicity.