[polymer] Merge of master into polymer10-migration

netlog_viewer/log_view_painter.js

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// TODO(eroman): put these methods into a namespace.
+
+var createLogEntryTablePrinter;
+var proxySettingsToString;
+var stripPrivacyInfo;
+
+// Start of anonymous namespace.
+(function() {
+'use strict';
+
+function canCollapseBeginWithEnd(beginEntry) {
+  return beginEntry &&
+         beginEntry.isBegin() &&
+         beginEntry.end &&
+         beginEntry.end.index == beginEntry.index + 1 &&
+         (!beginEntry.orig.params || !beginEntry.end.orig.params);
+}
+
+/**
+ * Creates a TablePrinter for use by the above two functions.  baseTime is
+ * the time relative to which other times are displayed.
+ */
+createLogEntryTablePrinter = function(logEntries, privacyStripping,
+                                      baseTime, logCreationTime) {
+  var entries = LogGroupEntry.createArrayFrom(logEntries);
+  var tablePrinter = new TablePrinter();
+  var parameterOutputter = new ParameterOutputter(tablePrinter);
+
+  if (entries.length == 0)
+    return tablePrinter;
+
+  var startTime = timeutil.convertTimeTicksToTime(entries[0].orig.time);
+
+  for (var i = 0; i < entries.length; ++i) {
+    var entry = entries[i];
+
+    // Avoid printing the END for a BEGIN that was immediately before, unless
+    // both have extra parameters.
+    if (!entry.isEnd() || !canCollapseBeginWithEnd(entry.begin)) {
+      var entryTime = timeutil.convertTimeTicksToTime(entry.orig.time);
+      addRowWithTime(tablePrinter, entryTime - baseTime, startTime - baseTime);
+
+      for (var j = entry.getDepth(); j > 0; --j)
+        tablePrinter.addCell('  ');
+
+      var eventText = getTextForEvent(entry);
+      // Get the elapsed time, and append it to the event text.
+      if (entry.isBegin()) {
+        var dt = '?';
+        // Definite time.
+        if (entry.end) {
+          dt = entry.end.orig.time - entry.orig.time;
+        } else if (logCreationTime != undefined) {
+          dt = (logCreationTime - entryTime) + '+';
+        }
+        eventText += '  [dt=' + dt + ']';
+      }
+
+      var mainCell = tablePrinter.addCell(eventText);
+      mainCell.allowOverflow = true;
+    }
+
+    // Output the extra parameters.
+    if (typeof entry.orig.params == 'object') {
+      // Those 5 skipped cells are: two for "t=", and three for "st=".
+      tablePrinter.setNewRowCellIndent(5 + entry.getDepth());
+      writeParameters(entry.orig, privacyStripping, parameterOutputter);
+
+      tablePrinter.setNewRowCellIndent(0);
+    }
+  }
+
+  // If viewing a saved log file, add row with just the time the log was
+  // created, if the event never completed.
+  var lastEntry = entries[entries.length - 1];
+  // If the last entry has a non-zero depth or is a begin event, the source is
+  // still active.
+  var isSourceActive = lastEntry.getDepth() != 0 || lastEntry.isBegin();
+  if (logCreationTime != undefined && isSourceActive) {
+    addRowWithTime(tablePrinter,
+                   logCreationTime - baseTime,
+                   startTime - baseTime);
+  }
+
+  return tablePrinter;
+};
+
+/**
+ * Adds a new row to the given TablePrinter, and adds five cells containing
+ * information about the time an event occured.
+ * Format is '[t=<time of the event in ms>] [st=<ms since the source started>]'.
+ * @param {TablePrinter} tablePrinter The table printer to add the cells to.
+ * @param {number} eventTime The time the event occured, in milliseconds,
+ *     relative to some base time.
+ * @param {number} startTime The time the first event for the source occured,
+ *     relative to the same base time as eventTime.
+ */
+function addRowWithTime(tablePrinter, eventTime, startTime) {
+  tablePrinter.addRow();
+  tablePrinter.addCell('t=');
+  var tCell = tablePrinter.addCell(eventTime);
+  tCell.alignRight = true;
+  tablePrinter.addCell(' [st=');
+  var stCell = tablePrinter.addCell(eventTime - startTime);
+  stCell.alignRight = true;
+  tablePrinter.addCell('] ');
+}
+
+/**
+ * |hexString| must be a string of hexadecimal characters with no whitespace,
+ * whose length is a multiple of two.  Writes multiple lines to |out| with
+ * the hexadecimal characters from |hexString| on the left, in groups of
+ * two, and their corresponding ASCII characters on the right.
+ *
+ * 16 bytes will be placed on each line of the output string, split into two
+ * columns of 8.
+ */
+function writeHexString(hexString, out) {
+  var asciiCharsPerLine = 16;
+  // Number of transferred bytes in a line of output.  Length of a
+  // line is roughly 4 times larger.
+  var hexCharsPerLine = 2 * asciiCharsPerLine;
+  for (var i = 0; i < hexString.length; i += hexCharsPerLine) {
+    var hexLine = '';
+    var asciiLine = '';
+    for (var j = i; j < i + hexCharsPerLine && j < hexString.length; j += 2) {
+      // Split into two columns of 8 bytes each.
+      if (j == i + hexCharsPerLine / 2)
+        hexLine += ' ';
+      var hex = hexString.substr(j, 2);
+      hexLine += hex + ' ';
+      var charCode = parseInt(hex, 16);
+      // For ASCII codes 32 though 126, display the corresponding
+      // characters.  Use a space for nulls, and a period for
+      // everything else.
+      if (charCode >= 0x20 && charCode <= 0x7E) {
+        asciiLine += String.fromCharCode(charCode);
+      } else if (charCode == 0x00) {
+        asciiLine += ' ';
+      } else {
+        asciiLine += '.';
+      }
+    }
+
+    // Make the ASCII text for the last line of output align with the previous
+    // lines.
+    hexLine += makeRepeatedString(' ',
+                                  3 * asciiCharsPerLine + 1 - hexLine.length);
+    out.writeLine('   ' + hexLine + '  ' + asciiLine);
+  }
+}
+
+/**
+ * Wrapper around a TablePrinter to simplify outputting lines of text for event
+ * parameters.
+ */
+var ParameterOutputter = (function() {
+  /**
+   * @constructor
+   */
+  function ParameterOutputter(tablePrinter) {
+    this.tablePrinter_ = tablePrinter;
+  }
+
+  ParameterOutputter.prototype = {
+    /**
+     * Outputs a single line.
+     */
+    writeLine: function(line) {
+      this.tablePrinter_.addRow();
+      var cell = this.tablePrinter_.addCell(line);
+      cell.allowOverflow = true;
+      return cell;
+    },
+
+    /**
+     * Outputs a key=value line which looks like:
+     *
+     *   --> key = value
+     */
+    writeArrowKeyValue: function(key, value, link) {
+      var cell = this.writeLine(kArrow + key + ' = ' + value);
+      cell.link = link;
+    },
+
+    /**
+     * Outputs a key= line which looks like:
+     *
+     *   --> key =
+     */
+    writeArrowKey: function(key) {
+      this.writeLine(kArrow + key + ' =');
+    },
+
+    /**
+     * Outputs multiple lines, each indented by numSpaces.
+     * For instance if numSpaces=8 it might look like this:
+     *
+     *         line 1
+     *         line 2
+     *         line 3
+     */
+    writeSpaceIndentedLines: function(numSpaces, lines) {
+      var prefix = makeRepeatedString(' ', numSpaces);
+      for (var i = 0; i < lines.length; ++i)
+        this.writeLine(prefix + lines[i]);
+    },
+
+    /**
+     * Outputs multiple lines such that the first line has
+     * an arrow pointing at it, and subsequent lines
+     * align with the first one. For example:
+     *
+     *   --> line 1
+     *       line 2
+     *       line 3
+     */
+    writeArrowIndentedLines: function(lines) {
+      if (lines.length == 0)
+        return;
+
+      this.writeLine(kArrow + lines[0]);
+
+      for (var i = 1; i < lines.length; ++i)
+        this.writeLine(kArrowIndentation + lines[i]);
+    }
+  };
+
+  var kArrow = ' --> ';
+  var kArrowIndentation = '     ';
+
+  return ParameterOutputter;
+})();  // end of ParameterOutputter
+
+/**
+ * Formats the parameters for |entry| and writes them to |out|.
+ * Certain event types have custom pretty printers. Everything else will
+ * default to a JSON-like format.
+ */
+function writeParameters(entry, privacyStripping, out) {
+  if (privacyStripping) {
+    // If privacy stripping is enabled, remove data as needed.
+    entry = stripPrivacyInfo(entry);
+  } else {
+    // If headers are in an object, convert them to an array for better display.
+    entry = reformatHeaders(entry);
+  }
+
+  // Use any parameter writer available for this event type.
+  var paramsWriter = getParamaterWriterForEventType(entry.type);
+  var consumedParams = {};
+  if (paramsWriter)
+    paramsWriter(entry, out, consumedParams);
+
+  // Write any un-consumed parameters.
+  for (var k in entry.params) {
+    if (consumedParams[k])
+      continue;
+    defaultWriteParameter(k, entry.params[k], out);
+  }
+}
+
+/**
+ * Finds a writer to format the parameters for events of type |eventType|.
+ *
+ * @return {function} The returned function "writer" can be invoked
+ *                    as |writer(entry, writer, consumedParams)|. It will
+ *                    output the parameters of |entry| to |out|, and fill
+ *                    |consumedParams| with the keys of the parameters
+ *                    consumed. If no writer is available for |eventType| then
+ *                    returns null.
+ */
+function getParamaterWriterForEventType(eventType) {
+  switch (eventType) {
+    case EventType.HTTP_TRANSACTION_SEND_REQUEST_HEADERS:
+    case EventType.HTTP_TRANSACTION_SEND_TUNNEL_HEADERS:
+    case EventType.TYPE_HTTP_CACHE_CALLER_REQUEST_HEADERS:
+      return writeParamsForRequestHeaders;
+
+    case EventType.PROXY_CONFIG_CHANGED:
+      return writeParamsForProxyConfigChanged;
+
+    case EventType.CERT_VERIFIER_JOB:
+    case EventType.SSL_CERTIFICATES_RECEIVED:
+      return writeParamsForCertificates;
+    case EventType.EV_CERT_CT_COMPLIANCE_CHECKED:
+      return writeParamsForCheckedEVCertificates;
+
+    case EventType.SSL_VERSION_FALLBACK:
+      return writeParamsForSSLVersionFallback;
+  }
+  return null;
+}
+
+/**
+ * Default parameter writer that outputs a visualization of field named |key|
+ * with value |value| to |out|.
+ */
+function defaultWriteParameter(key, value, out) {
+  if (key == 'headers' && value instanceof Array) {
+    out.writeArrowIndentedLines(value);
+    return;
+  }
+
+  // For transferred bytes, display the bytes in hex and ASCII.
+  if (key == 'hex_encoded_bytes' && typeof value == 'string') {
+    out.writeArrowKey(key);
+    writeHexString(value, out);
+    return;
+  }
+
+  // Handle source_dependency entries - add link and map source type to
+  // string.
+  if (key == 'source_dependency' && typeof value == 'object') {
+    var link = '#events&s=' + value.id;
+    var valueStr = value.id + ' (' + EventSourceTypeNames[value.type] + ')';
+    out.writeArrowKeyValue(key, valueStr, link);
+    return;
+  }
+
+  if (key == 'net_error' && typeof value == 'number') {
+    var valueStr = value + ' (' + netErrorToString(value) + ')';
+    out.writeArrowKeyValue(key, valueStr);
+    return;
+  }
+
+  if (key == 'quic_error' && typeof value == 'number') {
+    var valueStr = value + ' (' + quicErrorToString(value) + ')';
+    out.writeArrowKeyValue(key, valueStr);
+    return;
+  }
+
+  if (key == 'quic_crypto_handshake_message' && typeof value == 'string') {
+    var lines = value.split('\n');
+    out.writeArrowIndentedLines(lines);
+    return;
+  }
+
+  if (key == 'quic_rst_stream_error' && typeof value == 'number') {
+    var valueStr = value + ' (' + quicRstStreamErrorToString(value) + ')';
+    out.writeArrowKeyValue(key, valueStr);
+    return;
+  }
+
+  if (key == 'load_flags' && typeof value == 'number') {
+    var valueStr = value + ' (' + getLoadFlagSymbolicString(value) + ')';
+    out.writeArrowKeyValue(key, valueStr);
+    return;
+  }
+
+  if (key == 'load_state' && typeof value == 'number') {
+    var valueStr = value + ' (' + getKeyWithValue(LoadState, value) + ')';
+    out.writeArrowKeyValue(key, valueStr);
+    return;
+  }
+
+  if (key == 'sdch_problem_code' && typeof value == 'number') {
+    var valueStr = value + ' (' + sdchProblemCodeToString(value) + ')';
+    out.writeArrowKeyValue(key, valueStr);
+    return;
+  }
+
+  // Otherwise just default to JSON formatting of the value.
+  out.writeArrowKeyValue(key, JSON.stringify(value));
+}
+
+/**
+ * Returns the set of LoadFlags that make up the integer |loadFlag|.
+ * For example: getLoadFlagSymbolicString(
+ */
+function getLoadFlagSymbolicString(loadFlag) {
+
+  return getSymbolicString(loadFlag, LoadFlag,
+                           getKeyWithValue(LoadFlag, loadFlag));
+}
+
+/**
+ * Returns the set of CertStatusFlags that make up the integer |certStatusFlag|
+ */
+function getCertStatusFlagSymbolicString(certStatusFlag) {
+  return getSymbolicString(certStatusFlag, CertStatusFlag, '');
+}
+
+/**
+ * Returns a string representing the flags composing the given bitmask.
+ */
+function getSymbolicString(bitmask, valueToName, zeroName) {
+  var matchingFlagNames = [];
+
+  for (var k in valueToName) {
+    if (bitmask & valueToName[k])
+      matchingFlagNames.push(k);
+  }
+
+  // If no flags were matched, returns a special value.
+  if (matchingFlagNames.length == 0)
+    return zeroName;
+
+  return matchingFlagNames.join(' | ');
+}
+
+/**
+ * Converts an SSL version number to a textual representation.
+ * For instance, SSLVersionNumberToName(0x0301) returns 'TLS 1.0'.
+ */
+function SSLVersionNumberToName(version) {
+  if ((version & 0xFFFF) != version) {
+    // If the version number is more than 2 bytes long something is wrong.
+    // Print it as hex.
+    return 'SSL 0x' + version.toString(16);
+  }
+
+  // See if it is a known TLS name.
+  var kTLSNames = {
+    0x0301: 'TLS 1.0',
+    0x0302: 'TLS 1.1',
+    0x0303: 'TLS 1.2'
+  };
+  var name = kTLSNames[version];
+  if (name)
+    return name;
+
+  // Otherwise label it as an SSL version.
+  var major = (version & 0xFF00) >> 8;
+  var minor = version & 0x00FF;
+
+  return 'SSL ' + major + '.' + minor;
+}
+
+/**
+ * TODO(eroman): get rid of this, as it is only used by 1 callsite.
+ *
+ * Indent |lines| by |start|.
+ *
+ * For example, if |start| = ' -> ' and |lines| = ['line1', 'line2', 'line3']
+ * the output will be:
+ *
+ *   " -> line1\n" +
+ *   "    line2\n" +
+ *   "    line3"
+ */
+function indentLines(start, lines) {
+  return start + lines.join('\n' + makeRepeatedString(' ', start.length));
+}
+
+/**
+ * If entry.param.headers exists and is an object other than an array, converts
+ * it into an array and returns a new entry.  Otherwise, just returns the
+ * original entry.
+ */
+function reformatHeaders(entry) {
+  // If there are no headers, or it is not an object other than an array,
+  // return |entry| without modification.
+  if (!entry.params || entry.params.headers === undefined ||
+      typeof entry.params.headers != 'object' ||
+      entry.params.headers instanceof Array) {
+    return entry;
+  }
+
+  // Duplicate the top level object, and |entry.params|, so the original object
+  // will not be modified.
+  entry = shallowCloneObject(entry);
+  entry.params = shallowCloneObject(entry.params);
+
+  // Convert headers to an array.
+  var headers = [];
+  for (var key in entry.params.headers)
+    headers.push(key + ': ' + entry.params.headers[key]);
+  entry.params.headers = headers;
+
+  return entry;
+}
+
+/**
+ * Removes a cookie or unencrypted login information from a single HTTP header
+ * line, if present, and returns the modified line.  Otherwise, just returns
+ * the original line.
+ *
+ * Note: this logic should be kept in sync with
+ * net::ElideHeaderValueForNetLog in net/http/http_log_util.cc.
+ */
+function stripCookieOrLoginInfo(line) {
+  var patterns = [
+      // Cookie patterns
+      /^set-cookie: /i,
+      /^set-cookie2: /i,
+      /^cookie: /i,
+
+      // Unencrypted authentication patterns
+      /^authorization: \S*\s*/i,
+      /^proxy-authorization: \S*\s*/i];
+
+  // Prefix will hold the first part of the string that contains no private
+  // information.  If null, no part of the string contains private information.
+  var prefix = null;
+  for (var i = 0; i < patterns.length; i++) {
+    var match = patterns[i].exec(line);
+    if (match != null) {
+      prefix = match[0];
+      break;
+    }
+  }
+
+  // Look for authentication information from data received from the server in
+  // multi-round Negotiate authentication.
+  if (prefix === null) {
+    var challengePatterns = [
+        /^www-authenticate: (\S*)\s*/i,
+        /^proxy-authenticate: (\S*)\s*/i];
+    for (var i = 0; i < challengePatterns.length; i++) {
+      var match = challengePatterns[i].exec(line);
+      if (!match)
+        continue;
+
+      // If there's no data after the scheme name, do nothing.
+      if (match[0].length == line.length)
+        break;
+
+      // Ignore lines with commas, as they may contain lists of schemes, and
+      // the information we want to hide is Base64 encoded, so has no commas.
+      if (line.indexOf(',') >= 0)
+        break;
+
+      // Ignore Basic and Digest authentication challenges, as they contain
+      // public information.
+      if (/^basic$/i.test(match[1]) || /^digest$/i.test(match[1]))
+        break;
+
+      prefix = match[0];
+      break;
+    }
+  }
+
+  if (prefix) {
+    var suffix = line.slice(prefix.length);
+    // If private information has already been removed, keep the line as-is.
+    // This is often the case when viewing a loaded log.
+    if (suffix.search(/^\[[0-9]+ bytes were stripped\]$/) == -1) {
+      return prefix + '[' + suffix.length + ' bytes were stripped]';
+    }
+  }
+
+  return line;
+}
+
+/**
+ * Remove debug data from HTTP/2 GOAWAY frame due to privacy considerations, see
+ * https://httpwg.github.io/specs/rfc7540.html#GOAWAY.
+ *
+ * Note: this logic should be kept in sync with
+ * net::ElideGoAwayDebugDataForNetLog in net/http/http_log_util.cc.
+ */
+function stripGoAwayDebugData(value) {
+  return '[' + value.length + ' bytes were stripped]';
+}
+
+/**
+ * If |entry| has headers, returns a copy of |entry| with all cookie and
+ * unencrypted login text removed.  Otherwise, returns original |entry| object.
+ * This is needed so that JSON log dumps can be made without affecting the
+ * source data.  Converts headers stored in objects to arrays.
+ */
+stripPrivacyInfo = function(entry) {
+  if (!entry.params) {
+    return entry;
+  }
+
+  if (entry.type == EventType.HTTP2_SESSION_GOAWAY &&
+      entry.params.debug_data != undefined) {
+    // Duplicate the top level object, and |entry.params|.  All other fields are
+    // just pointers to the original values, as they won't be modified, other
+    // than |entry.params.debug_data|.
+    entry = shallowCloneObject(entry);
+    entry.params = shallowCloneObject(entry.params);
+    entry.params.debug_data =
+        stripGoAwayDebugData(entry.params.debug_data);
+    return entry;
+  }
+
+  if (entry.params.headers === undefined ||
+      !(entry.params.headers instanceof Object)) {
+    return entry;
+  }
+
+  // Make sure entry's headers are in an array.
+  entry = reformatHeaders(entry);
+
+  // Duplicate the top level object, and |entry.params|.  All other fields are
+  // just pointers to the original values, as they won't be modified, other than
+  // |entry.params.headers|.
+  entry = shallowCloneObject(entry);
+  entry.params = shallowCloneObject(entry.params);
+
+  entry.params.headers = entry.params.headers.map(stripCookieOrLoginInfo);
+  return entry;
+};
+
+/**
+ * Outputs the request header parameters of |entry| to |out|.
+ */
+function writeParamsForRequestHeaders(entry, out, consumedParams) {
+  var params = entry.params;
+
+  if (!(typeof params.line == 'string') || !(params.headers instanceof Array)) {
+    // Unrecognized params.
+    return;
+  }
+
+  // Strip the trailing CRLF that params.line contains.
+  var lineWithoutCRLF = params.line.replace(/\r\n$/g, '');
+  out.writeArrowIndentedLines([lineWithoutCRLF].concat(params.headers));
+
+  consumedParams.line = true;
+  consumedParams.headers = true;
+}
+
+function writeCertificateParam(
+    certs_container, out, consumedParams, paramName) {
+  if (certs_container.certificates instanceof Array) {
+    var certs = certs_container.certificates.reduce(
+        function(previous, current) {
+          return previous.concat(current.split('\n'));
+        }, new Array());
+    out.writeArrowKey(paramName);
+    out.writeSpaceIndentedLines(8, certs);
+    consumedParams[paramName] = true;
+  }
+}
+
+/**
+ * Outputs the certificate parameters of |entry| to |out|.
+ */
+function writeParamsForCertificates(entry, out, consumedParams) {
+  writeCertificateParam(entry.params, out, consumedParams, 'certificates');
+
+  if (typeof(entry.params.verified_cert) == 'object')
+    writeCertificateParam(
+        entry.params.verified_cert, out, consumedParams, 'verified_cert');
+
+  if (typeof(entry.params.cert_status) == 'number') {
+    var valueStr = entry.params.cert_status + ' (' +
+        getCertStatusFlagSymbolicString(entry.params.cert_status) + ')';
+    out.writeArrowKeyValue('cert_status', valueStr);
+    consumedParams.cert_status = true;
+  }
+
+}
+
+function writeParamsForCheckedEVCertificates(entry, out, consumedParams) {
+  if (typeof(entry.params.certificate) == 'object')
+    writeCertificateParam(
+        entry.params.certificate, out, consumedParams, 'certificate');
+}
+
+/**
+ * Outputs the SSL version fallback parameters of |entry| to |out|.
+ */
+function writeParamsForSSLVersionFallback(entry, out, consumedParams) {
+  var params = entry.params;
+
+  if (typeof params.version_before != 'number' ||
+      typeof params.version_after != 'number') {
+    // Unrecognized params.
+    return;
+  }
+
+  var line = SSLVersionNumberToName(params.version_before) +
+             ' ==> ' +
+             SSLVersionNumberToName(params.version_after);
+  out.writeArrowIndentedLines([line]);
+
+  consumedParams.version_before = true;
+  consumedParams.version_after = true;
+}
+
+function writeParamsForProxyConfigChanged(entry, out, consumedParams) {
+  var params = entry.params;
+
+  if (typeof params.new_config != 'object') {
+    // Unrecognized params.
+    return;
+  }
+
+  if (typeof params.old_config == 'object') {
+    var oldConfigString = proxySettingsToString(params.old_config);
+    // The previous configuration may not be present in the case of
+    // the initial proxy settings fetch.
+    out.writeArrowKey('old_config');
+
+    out.writeSpaceIndentedLines(8, oldConfigString.split('\n'));
+
+    consumedParams.old_config = true;
+  }
+
+  var newConfigString = proxySettingsToString(params.new_config);
+  out.writeArrowKey('new_config');
+  out.writeSpaceIndentedLines(8, newConfigString.split('\n'));
+
+  consumedParams.new_config = true;
+}
+
+function getTextForEvent(entry) {
+  var text = '';
+
+  if (entry.isBegin() && canCollapseBeginWithEnd(entry)) {
+    // Don't prefix with '+' if we are going to collapse the END event.
+    text = ' ';
+  } else if (entry.isBegin()) {
+    text = '+' + text;
+  } else if (entry.isEnd()) {
+    text = '-' + text;
+  } else {
+    text = ' ';
+  }
+
+  text += EventTypeNames[entry.orig.type];
+  return text;
+}
+
+proxySettingsToString = function(config) {
+  if (!config)
+    return '';
+
+  // TODO(eroman): if |config| has unexpected properties, print it as JSON
+  //               rather than hide them.
+
+  function getProxyListString(proxies) {
+    // Older versions of Chrome would set these values as strings, whereas newer
+    // logs use arrays.
+    // TODO(eroman): This behavior changed in M27. Support for older logs can
+    //               safely be removed circa M29.
+    if (Array.isArray(proxies)) {
+      var listString = proxies.join(', ');
+      if (proxies.length > 1)
+        return '[' + listString + ']';
+      return listString;
+    }
+    return proxies;
+  }
+
+  // The proxy settings specify up to three major fallback choices
+  // (auto-detect, custom pac url, or manual settings).
+  // We enumerate these to a list so we can later number them.
+  var modes = [];
+
+  // Output any automatic settings.
+  if (config.auto_detect)
+    modes.push(['Auto-detect']);
+  if (config.pac_url)
+    modes.push(['PAC script: ' + config.pac_url]);
+
+  // Output any manual settings.
+  if (config.single_proxy || config.proxy_per_scheme) {
+    var lines = [];
+
+    if (config.single_proxy) {
+      lines.push('Proxy server: ' + getProxyListString(config.single_proxy));
+    } else if (config.proxy_per_scheme) {
+      for (var urlScheme in config.proxy_per_scheme) {
+        if (urlScheme != 'fallback') {
+          lines.push('Proxy server for ' + urlScheme.toUpperCase() + ': ' +
+                     getProxyListString(config.proxy_per_scheme[urlScheme]));
+        }
+      }
+      if (config.proxy_per_scheme.fallback) {
+        lines.push('Proxy server for everything else: ' +
+                   getProxyListString(config.proxy_per_scheme.fallback));
+      }
+    }
+
+    // Output any proxy bypass rules.
+    if (config.bypass_list) {
+      if (config.reverse_bypass) {
+        lines.push('Reversed bypass list: ');
+      } else {
+        lines.push('Bypass list: ');
+      }
+
+      for (var i = 0; i < config.bypass_list.length; ++i)
+        lines.push('  ' + config.bypass_list[i]);
+    }
+
+    modes.push(lines);
+  }
+
+  var result = [];
+  if (modes.length < 1) {
+    // If we didn't find any proxy settings modes, we are using DIRECT.
+    result.push('Use DIRECT connections.');
+  } else if (modes.length == 1) {
+    // If there was just one mode, don't bother numbering it.
+    result.push(modes[0].join('\n'));
+  } else {
+    // Otherwise concatenate all of the modes into a numbered list
+    // (which correspond with the fallback order).
+    for (var i = 0; i < modes.length; ++i)
+      result.push(indentLines('(' + (i + 1) + ') ', modes[i]));
+  }
+
+  if (config.source != undefined && config.source != 'UNKNOWN')
+    result.push('Source: ' + config.source);
+
+  return result.join('\n');
+};
+
+// End of anonymous namespace.
+})();
+