PRESUBMIT: Improve PyLint check and add GN format check.

Add pylintrc file based on
https://code.google.com/p/chromium/codesearch#chromium/src/tools/perf/pylintrc
bit tightened up quite a bit (the one in depot_tools is far
more relaxed).

Remove a few excluded directories from pylint check and fixed/
suppressed all warnings generated.

Add GN format check + formatted all GN files using 'gn format'.
Cleanup redundant rules in tools/PRESUBMIT.py

TESTED=Ran 'git cl presubmit -vv', fixed the PyLint violations.
Ran it again with a modification in webrtc/build/webrtc.gni, formatted
all the GN files and ran it again.

R=henrika@webrtc.org, phoglund@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/50069004

Cr-Commit-Position: refs/heads/master@{#9274}

tools/python_charts/webrtc/__init__.py

@@ -5,4 +5,4 @@
 #  that can be found in the LICENSE file in the root of the source
 #  tree. An additional intellectual property rights grant can be found
 #  in the file PATENTS.  All contributing project authors may
-#  be found in the AUTHORS file in the root of the source tree.
+#  be found in the AUTHORS file in the root of the source tree.

tools/python_charts/webrtc/data_helper.py

@@ -89,7 +89,7 @@ class DataHelper(object):
     # We're going to have one dictionary per row.
     # Create that and copy frame_number values from the first data set
     for source_row in self.data_list[0]:
-      row_dict = { 'frame_number': source_row['frame_number'] }
+      row_dict = {'frame_number': source_row['frame_number']}
       result_data_table.append(row_dict)
 
     # Pick target field data points from the all data tables

tools/python_charts/webrtc/data_helper_test.py

@@ -18,7 +18,7 @@ class Test(unittest.TestCase):
                          {'frame_number': 1, 'ssim': 0.55, 'psnr': 30.55}]
     self.frame_data_1 = [{'frame_number': 0, 'ssim': 0.6, 'psnr': 30.6},
                          {'frame_number': 0, 'ssim': 0.66, 'psnr': 30.66}]
-    self.all_data = [ self.frame_data_0, self.frame_data_1 ]
+    self.all_data = [self.frame_data_0, self.frame_data_1]
 
     # Test with frame_number column in a non-first position sice we need to
     # support reordering that to be able to use the gviz_api as we want.

tools/python_charts/webrtc/main.py

@@ -37,7 +37,7 @@ def main():
   page_template_filename = '../templates/chart_page_template.html'
   # The data files must be located in the project tree for app engine being
   # able to access them.
-  data_filenames = [ '../data/vp8_sw.py', '../data/vp8_hw.py' ]
+  data_filenames = ['../data/vp8_sw.py', '../data/vp8_hw.py']
   # Will contain info/error messages to be displayed on the resulting page.
   messages = []
   # Load the page HTML template.