webkitpy: Add time output to the start of logging messages.

third_party/WebKit/Tools/Scripts/webkitpy/common/system/log_utils.py

Index: third_party/WebKit/Tools/Scripts/webkitpy/common/system/log_utils.py
diff --git a/third_party/WebKit/Tools/Scripts/webkitpy/common/system/log_utils.py b/third_party/WebKit/Tools/Scripts/webkitpy/common/system/log_utils.py
index a862bd5783ff7916fb61226101861a3386e29b50..75471196080056d7e40220791a5a40c21f89ecd4 100644
--- a/third_party/WebKit/Tools/Scripts/webkitpy/common/system/log_utils.py
+++ b/third_party/WebKit/Tools/Scripts/webkitpy/common/system/log_utils.py
@@ -28,11 +28,12 @@ import sys
 _log = logging.getLogger(__name__)
 
 
-def _default_handlers(stream, logging_level):
+def _default_handlers(stream, logging_level, include_time):
     """Return a list of the default logging handlers to use.
 
     Args:
       stream: See the configure_logging() docstring.
+      include_time: See the configure_logging() docstring.
     """
     # Create the filter.
     def should_log(record):
@@ -46,10 +47,15 @@ def _default_handlers(stream, logging_level):
 
     # Create the handler.
     handler = logging.StreamHandler(stream)
+    if include_time:
+        prefix = '%(asctime)s - '
+    else:
+        prefix = ''
+
     if logging_level == logging.DEBUG:
-        formatter = logging.Formatter('%(name)s: [%(levelname)s] %(message)s')
+        formatter = logging.Formatter(prefix + '%(name)s: [%(levelname)s] %(message)s')
     else:
-        formatter = logging.Formatter('%(message)s')
+        formatter = logging.Formatter(prefix + '%(message)s')
 
     handler.setFormatter(formatter)
     handler.addFilter(logging_filter)
@@ -58,7 +64,7 @@ def _default_handlers(stream, logging_level):
 
 
 def configure_logging(logging_level=None, logger=None, stream=None,
-                      handlers=None):
+                      handlers=None, include_time=True):
     """Configure logging for standard purposes.
 
     Returns:
@@ -80,6 +86,9 @@ def configure_logging(logging_level=None, logger=None, stream=None,
       handlers: A list of logging.Handler instances to add to the logger
                 being configured.  If this parameter is provided, then the
                 stream parameter is not used.
+      include_time: Include time information at the start of every log message.
+                    Useful for understanding how much time has passed between
+                    subsequent log messages.
     """
     # If the stream does not define an "encoding" data attribute, the
     # logging module can throw an error like the following:
@@ -96,7 +105,7 @@ def configure_logging(logging_level=None, logger=None, stream=None,
     if stream is None:
         stream = sys.stderr
     if handlers is None:
-        handlers = _default_handlers(stream, logging_level)
+        handlers = _default_handlers(stream, logging_level, include_time)
 
     logger.setLevel(logging_level)