Bug 1344832 - Enable flake8 rule E502: "the backslash is redundant between brackets". r+dexter r=Dexter

This patch enables flake8 rule E502:
"the backslash is redundant between brackets" in toolkit/components/telemetry
by removing the relative E502 entry from toolkit/components/telemetry/.flake8
and fixing the files for which the E502 error was reported.
Precisely 8 errors violating E502 rule were found and solved.

MozReview-Commit-ID: 1z8f3JjJ2gt

--HG--
extra : rebase_source : de0622506a4a5a074ea5afa739b8537832aa4096

toolkit/components/telemetry/.flake8

@@ -1,5 +1,5 @@
 [flake8]
 # See http://pep8.readthedocs.io/en/latest/intro.html#configuration
-ignore = E121, E123, E126, E129, E133, E226, E241, E242, E704, W503, E402, E502, E128, E501, E713, E222, E201, E202, W602, E127, W601
+ignore = E121, E123, E126, E129, E133, E226, E241, E242, E704, W503, E402, E128, E501, E713, E222, E201, E202, W602, E127, W601
 max-line-length = 99
 filename = *.py, +.lint

toolkit/components/telemetry/gen-histogram-data.py

@@ -20,7 +20,7 @@ def print_array_entry(output, histogram, name_index, exp_index, label_index, lab
     cpp_guard = histogram.cpp_guard()
     if cpp_guard:
         print("#if defined(%s)" % cpp_guard, file=output)
-    print("  { %s, %s, %s, %s, %d, %d, %s, %d, %d, %s }," \
+    print("  { %s, %s, %s, %s, %d, %d, %s, %d, %d, %s },"
         % (histogram.low(),
            histogram.high(),
            histogram.n_buckets(),

toolkit/components/telemetry/gen-scalar-data.py

@@ -41,7 +41,7 @@ def write_scalar_info(scalar, output, name_index, expiration_index):
     if cpp_guard:
         print("#if defined(%s)" % cpp_guard, file=output)
 
-    print("  {{ {}, {}, {}, {}, {}, {} }},"\
+    print("  {{ {}, {}, {}, {}, {}, {} }},"
           .format(scalar.nsITelemetry_kind,
                   name_index,
                   expiration_index,

toolkit/components/telemetry/parse_events.py

@@ -134,10 +134,10 @@ def type_check_event_fields(identifier, name, definition):
 def string_check(identifier, field, value, min_length=1, max_length=None, regex=None):
     # Length check.
     if len(value) < min_length:
-        raise ValueError("%s: value '%s' for field %s is less than minimum length of %d" %\
+        raise ValueError("%s: value '%s' for field %s is less than minimum length of %d" %
                          (identifier, value, field, min_length))
     if max_length and len(value) > max_length:
-        raise ValueError("%s: value '%s' for field %s is greater than maximum length of %d" %\
+        raise ValueError("%s: value '%s' for field %s is greater than maximum length of %d" %
                          (identifier, value, field, max_length))
     # Regex check.
     if regex and not re.match(regex, value):

toolkit/components/telemetry/parse_scalars.py

@@ -48,7 +48,7 @@ class ScalarType:
         MAX_NAME_LENGTH = 40
         for n in [group_name, probe_name]:
             if len(n) > MAX_NAME_LENGTH:
-                raise ValueError("Name '{}' exceeds maximum name length of {} characters."\
+                raise ValueError("Name '{}' exceeds maximum name length of {} characters."
                                 .format(n, MAX_NAME_LENGTH))
 
         def check_name(name, error_msg_prefix, allowed_char_regexp):
@@ -60,7 +60,7 @@ class ScalarType:
             # Don't allow leading/trailing digits, '.' or '_'.
             if re.search(r'(^[\d\._])|([\d\._])$', name):
                 raise ValueError(error_msg_prefix +
-                    " name must not have a leading/trailing digit, a dot or underscore. Got: '{}'"\
+                    " name must not have a leading/trailing digit, a dot or underscore. Got: '{}'"
                     .format(name))
 
         check_name(group_name, 'Group', r'\.')
@@ -114,7 +114,7 @@ class ScalarType:
             raise KeyError(self._name + ' - unknown fields: ' + ', '.join(unknown_fields))
 
         # Checks the type for all the fields.
-        wrong_type_names = ['{} must be {}'.format(f, ALL_FIELDS[f].__name__) \
+        wrong_type_names = ['{} must be {}'.format(f, ALL_FIELDS[f].__name__)
             for f in definition.keys() if not isinstance(definition[f], ALL_FIELDS[f])]
         if len(wrong_type_names) > 0:
             raise TypeError(self._name + ' - ' + ', '.join(wrong_type_names))
@@ -236,7 +236,7 @@ class ScalarType:
         # behaviour for it.
         release_channel_collection = \
             self._definition.get('release_channel_collection', 'opt-in')
-        return 'nsITelemetry::' +  ('DATASET_RELEASE_CHANNEL_OPTOUT' \
+        return 'nsITelemetry::' +  ('DATASET_RELEASE_CHANNEL_OPTOUT'
             if release_channel_collection == 'opt-out' else 'DATASET_RELEASE_CHANNEL_OPTIN')
 
     @property