Adds new logging type SYSLOG which logs to the system log.

On Windows this type logs to the Event Log and on POSIX systems it logs to the messages log (or its equvalent).

As a side effect of adding the presubmit check for it this
CL fixes running the presumbit checks tests on Windows.

BUG=642115

Review-Url: https://codereview.chromium.org/2296783002
Cr-Commit-Position: refs/heads/master@{#419758}

diff --git a/PRESUBMIT_test_mocks.py b/PRESUBMIT_test_mocks.py
index 109b782c..772f405 100644
--- a/PRESUBMIT_test_mocks.py
+++ b/PRESUBMIT_test_mocks.py

@@ -22,6 +22,7 @@
     self.os_path = os.path
     self.platform = sys.platform
     self.python_executable = sys.executable
+    self.platform = sys.platform
     self.subprocess = subprocess
     self.files = []
     self.is_committing = False
@@ -122,6 +123,10 @@
     """os.path.basename is called on MockFile so we need a get method."""
     return self._local_path[i]
 
+  def __len__(self):
+    """os.path.basename is called on MockFile so we need a len method."""
+    return len(self._local_path)
+
 
 class MockAffectedFile(MockFile):
   def AbsoluteLocalPath(self):