Derive ChromiumPort from WebKitPort to add support for missing symbols to skip tests

Derive ChromiumPort from WebKitPort to add support for missing symbols to skip tests
https://bugs.webkit.org/show_bug.cgi?id=89706

Reviewed by Adam Barth.

Based on the original patch by Raymond Toy.

This patch changes ChromiumPort to derive from webkit.WebKitPort
instead of base.Port. This is a long-awaited change and a
precursor to merging base.Port and webkit.WebKitPort, but is
driven by the desire to dynamically detect whether the MP3 and
AAC codecs are compiled into DRT on Chromium, for which we
wanted to re-use the existing logic in WebKit port for determine
what to skip at compile time.

Most of the changes are shuffling things around so that we don't
change any other logic and so we override the necessary methods
in WebKitPort (and try to follow the same method definition
order where possible).

Also, on the Chromium port the mp3 and aac codecs are actually
defined in a separate library, so scanning webcore isn't
sufficient. This patch generalizes the symbol lookup to handle
multiple libraries, and uses different libraries as appropriate
for Chromium.

The only functional/visible changes should be in the value
returned for skipped_layout_tests().

* Scripts/webkitpy/layout_tests/port/chromium.py:
(ChromiumPort):
(ChromiumPort.__init__):
(ChromiumPort.driver_name):
(ChromiumPort._driver_class):
(ChromiumPort._missing_symbol_to_skipped_tests):
(ChromiumPort.skipped_layout_tests):
(ChromiumPort.setup_test_run):
(ChromiumPort._path_to_image_diff):
(ChromiumPort._convert_path):
* Scripts/webkitpy/layout_tests/port/chromium_unittest.py:
(ChromiumPortTest.test_missing_symbol_to_skipped_tests):
* Scripts/webkitpy/layout_tests/port/chromium_linux.py:
(ChromiumLinuxPort._modules_to_search_for_symbols):
* Scripts/webkitpy/layout_tests/port/chromium_mac.py:
(ChromiumLinuxPort._modules_to_search_for_symbols):
* Scripts/webkitpy/layout_tests/port/chromium_win.py:
(ChromiumLinuxPort._modules_to_search_for_symbols):
* Scripts/webkitpy/layout_tests/port/webkit.py:
(WebKitPort):
(WebKitPort.__init__):
(WebKitPort._symbols_string):
(WebKitPort._modules_to_search_for_symbols):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@121363 268f45cc-cd09-0410-ab3c-d52691b4dbfc