Enhance and refactor ChromeDriver's capability handling. Log warning for

non-recognized capabilities, return errors on incorrect input types,
and allow new format where all options are placed under a chromeOptions
dictionary.
The latter is needed to simplify handling capabilities on the WebDriver
client side. See http://codereview.appspot.com/5307047/.
BUG=82895,94721
TEST=none


Review URL: http://codereview.chromium.org/8341044

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@107629 0039d316-1c4b-4281-b951-d872f2087c98

8 files changed, 632 insertions, 177 deletions

diff --git a/chrome/chrome_tests.gypi b/chrome/chrome_tests.gypi
index 6ef71d9..cc30bd3 100644
--- a/chrome/chrome_tests.gypi
+++ b/chrome/chrome_tests.gypi
@@ -934,6 +934,8 @@
         'test/webdriver/webdriver_automation.h',
         'test/webdriver/webdriver_basic_types.cc',
         'test/webdriver/webdriver_basic_types.h',
+        'test/webdriver/webdriver_capabilities_parser.cc',
+        'test/webdriver/webdriver_capabilities_parser.h',
         'test/webdriver/webdriver_dispatch.cc',
         'test/webdriver/webdriver_dispatch.h',
         'test/webdriver/webdriver_element_id.cc',
@@ -1035,6 +1037,7 @@
         'test/webdriver/frame_path_unittest.cc',
         'test/webdriver/http_response_unittest.cc',
         'test/webdriver/keycode_text_conversion_unittest.cc',
+        'test/webdriver/webdriver_capabilities_parser_unittest.cc',
         'test/webdriver/webdriver_dispatch_unittest.cc',
         'test/webdriver/webdriver_key_converter_unittest.cc',
         'test/webdriver/webdriver_test_util.cc',
diff --git a/chrome/test/webdriver/commands/create_session.cc b/chrome/test/webdriver/commands/create_session.cc
index 84bdd5d..fd16c0b 100644
--- a/chrome/test/webdriver/commands/create_session.cc
+++ b/chrome/test/webdriver/commands/create_session.cc
@@ -4,59 +4,21 @@
 
 #include "chrome/test/webdriver/commands/create_session.h"
 
-#include <sstream>
 #include <string>
 
-#include "base/base64.h"
 #include "base/command_line.h"
 #include "base/file_path.h"
-#include "base/file_util.h"
 #include "base/logging.h"
 #include "base/scoped_temp_dir.h"
-#include "base/string_number_conversions.h"
-#include "base/stringprintf.h"
 #include "base/values.h"
-#include "chrome/app/chrome_command_ids.h"
-#include "chrome/common/chrome_constants.h"
-#include "chrome/common/chrome_switches.h"
-#include "chrome/common/zip.h"
 #include "chrome/test/webdriver/commands/response.h"
+#include "chrome/test/webdriver/webdriver_capabilities_parser.h"
 #include "chrome/test/webdriver/webdriver_error.h"
 #include "chrome/test/webdriver/webdriver_session.h"
 #include "chrome/test/webdriver/webdriver_session_manager.h"
 
 namespace webdriver {
 
-namespace {
-
-bool WriteBase64DataToFile(const FilePath& filename,
-                           const std::string& base64data,
-                           std::string* error_msg) {
-  std::string data;
-  if (!base::Base64Decode(base64data, &data)) {
-    *error_msg = "Invalid base64 encoded data.";
-    return false;
-  }
-  if (!file_util::WriteFile(filename, data.c_str(), data.length())) {
-    *error_msg = "Could not write data to file.";
-    return false;
-  }
-  return true;
-}
-
-Error* GetBooleanCapability(
-    const base::DictionaryValue* dict, const std::string& key, bool* option) {
-  Value* value = NULL;
-  if (dict->GetWithoutPathExpansion(key, &value)) {
-    if (!value->GetAsBoolean(option)) {
-      return new Error(kUnknownError, key + " must be a boolean");
-    }
-  }
-  return NULL;
-}
-
-}  // namespace
-
 CreateSession::CreateSession(const std::vector<std::string>& path_segments,
                              const DictionaryValue* const parameters)
     : Command(path_segments, parameters) {}
@@ -66,146 +28,42 @@ CreateSession::~CreateSession() {}
 bool CreateSession::DoesPost() { return true; }
 
 void CreateSession::ExecutePost(Response* const response) {
-  DictionaryValue *capabilities = NULL;
-  if (!GetDictionaryParameter("desiredCapabilities", &capabilities)) {
+  DictionaryValue* dict;
+  if (!GetDictionaryParameter("desiredCapabilities", &dict)) {
     response->SetError(new Error(
         kBadRequest, "Missing or invalid 'desiredCapabilities'"));
     return;
   }
-
-  Automation::BrowserOptions browser_options;
-  FilePath::StringType path;
-  if (capabilities->GetStringWithoutPathExpansion("chrome.binary", &path))
-    browser_options.command = CommandLine(FilePath(path));
-
-  ListValue* switches = NULL;
-  const char* kCustomSwitchesKey = "chrome.switches";
-  if (capabilities->GetListWithoutPathExpansion(kCustomSwitchesKey,
-                                                &switches)) {
-    for (size_t i = 0; i < switches->GetSize(); ++i) {
-      std::string switch_string;
-      if (!switches->GetString(i, &switch_string)) {
-        response->SetError(new Error(
-            kBadRequest, "Custom switch is not a string"));
-        return;
-      }
-      size_t separator_index = switch_string.find("=");
-      if (separator_index != std::string::npos) {
-        CommandLine::StringType switch_string_native;
-        if (!switches->GetString(i, &switch_string_native)) {
-          response->SetError(new Error(
-              kBadRequest, "Custom switch is not a string"));
-          return;
-        }
-        browser_options.command.AppendSwitchNative(
-            switch_string.substr(0, separator_index),
-            switch_string_native.substr(separator_index + 1));
-      } else {
-        browser_options.command.AppendSwitch(switch_string);
-      }
-    }
-  } else if (capabilities->HasKey(kCustomSwitchesKey)) {
-    response->SetError(new Error(
-        kBadRequest, "Custom switches must be a list"));
-    return;
-  }
-
-  Value* verbose_value;
-  if (capabilities->GetWithoutPathExpansion("chrome.verbose", &verbose_value)) {
-    bool verbose = false;
-    if (verbose_value->GetAsBoolean(&verbose)) {
-      // Since logging is shared among sessions, if any session requests verbose
-      // logging, verbose logging will be enabled for all sessions. It is not
-      // possible to turn it off.
-      if (verbose)
-        logging::SetMinLogLevel(logging::LOG_INFO);
-    } else {
-      response->SetError(new Error(
-          kBadRequest, "verbose must be a boolean true or false"));
-      return;
-    }
-  }
-
-  capabilities->GetStringWithoutPathExpansion(
-      "chrome.channel", &browser_options.channel_id);
-
-  ScopedTempDir temp_profile_dir;
-  std::string base64_profile;
-  if (capabilities->GetStringWithoutPathExpansion("chrome.profile",
-                                                  &base64_profile)) {
-    if (!temp_profile_dir.CreateUniqueTempDir()) {
-      response->SetError(new Error(
-          kBadRequest, "Could not create temporary profile directory."));
-      return;
-    }
-    FilePath temp_profile_zip(
-        temp_profile_dir.path().AppendASCII("profile.zip"));
-    std::string message;
-    if (!WriteBase64DataToFile(temp_profile_zip, base64_profile, &message)) {
-      response->SetError(new Error(kBadRequest, message));
-      return;
-    }
-
-    browser_options.user_data_dir =
-        temp_profile_dir.path().AppendASCII("user_data_dir");
-    if (!zip::Unzip(temp_profile_zip, browser_options.user_data_dir)) {
-      response->SetError(new Error(
-          kBadRequest, "Could not unarchive provided user profile"));
-      return;
-    }
-  }
-
-  const char* kExtensions = "chrome.extensions";
-  ScopedTempDir extensions_dir;
-  ListValue* extensions_list = NULL;
-  std::vector<FilePath> extensions;
-  if (capabilities->GetListWithoutPathExpansion(kExtensions,
-                                                &extensions_list)) {
-    if (!extensions_dir.CreateUniqueTempDir()) {
-      response->SetError(new Error(
-          kBadRequest, "Could create temporary extensions directory."));
-      return;
-    }
-    for (size_t i = 0; i < extensions_list->GetSize(); ++i) {
-      std::string base64_extension;
-      if (!extensions_list->GetString(i, &base64_extension)) {
-        response->SetError(new Error(
-            kBadRequest, "Extension must be a base64 encoded string."));
-        return;
-      }
-      FilePath extension_file(
-          extensions_dir.path().AppendASCII("extension" +
-                                            base::IntToString(i) + ".crx"));
-      std::string message;
-      if (!WriteBase64DataToFile(extension_file, base64_extension, &message)) {
-        response->SetError(new Error(kBadRequest, message));
-        return;
-      }
-      extensions.push_back(extension_file);
-    }
-  } else if (capabilities->HasKey(kExtensions)) {
+  ScopedTempDir temp_dir;
+  if (!temp_dir.CreateUniqueTempDir()) {
     response->SetError(new Error(
-        kBadRequest, "Extensions must be a list of base64 encoded strings"));
+        kUnknownError, "Unable to create temp directory for unpacking"));
     return;
   }
-
-  Session::Options session_options;
-  Error* error = NULL;
-  error = GetBooleanCapability(capabilities, "chrome.nativeEvents",
-                               &session_options.use_native_events);
-  if (!error) {
-    error = GetBooleanCapability(capabilities, "chrome.loadAsync",
-                                 &session_options.load_async);
-  }
-  if (!error) {
-    error = GetBooleanCapability(capabilities, "chrome.detach",
-                                 &browser_options.detach_process);
-  }
+  Capabilities caps;
+  CapabilitiesParser parser(dict, temp_dir.path(), &caps);
+  Error* error = parser.Parse();
   if (error) {
     response->SetError(error);
     return;
   }
 
+  // Since logging is shared among sessions, if any session requests verbose
+  // logging, verbose logging will be enabled for all sessions. It is not
+  // possible to turn it off.
+  if (caps.verbose)
+    logging::SetMinLogLevel(logging::LOG_INFO);
+
+  Session::Options session_options;
+  session_options.load_async = caps.load_async;
+  session_options.use_native_events = caps.native_events;
+
+  Automation::BrowserOptions browser_options;
+  browser_options.command = caps.command;
+  browser_options.channel_id = caps.channel;
+  browser_options.detach_process = caps.detach;
+  browser_options.user_data_dir = caps.profile;
+
   // Session manages its own liftime, so do not call delete.
   Session* session = new Session(session_options);
   error = session->Init(browser_options);
@@ -215,8 +73,8 @@ void CreateSession::ExecutePost(Response* const response) {
   }
 
   // Install extensions.
-  for (size_t i = 0; i < extensions.size(); ++i) {
-    Error* error = session->InstallExtension(extensions[i]);
+  for (size_t i = 0; i < caps.extensions.size(); ++i) {
+    Error* error = session->InstallExtension(caps.extensions[i]);
     if (error) {
       response->SetError(error);
       return;
diff --git a/chrome/test/webdriver/commands/session_with_id.cc b/chrome/test/webdriver/commands/session_with_id.cc
index b3155e2..5a95814 100644
--- a/chrome/test/webdriver/commands/session_with_id.cc
+++ b/chrome/test/webdriver/commands/session_with_id.cc
@@ -49,9 +49,20 @@ void SessionWithID::ExecuteGet(Response* const response) {
   temp_value->SetString("platform", "unknown");
 #endif
 
-  temp_value->SetBoolean("cssSelectorsEnabled", true);
   temp_value->SetBoolean("javascriptEnabled", true);
   temp_value->SetBoolean("takesScreenshot", true);
+  temp_value->SetBoolean("handlesAlerts", true);
+  temp_value->SetBoolean("databaseEnabled", false);
+  temp_value->SetBoolean("locationContextEnabled", false);
+  temp_value->SetBoolean("applicationCacheEnabled", false);
+  temp_value->SetBoolean("browserConnectionEnabled", false);
+  temp_value->SetBoolean("cssSelectorsEnabled", true);
+  temp_value->SetBoolean("webStorageEnabled", false);
+  temp_value->SetBoolean("rotatable", false);
+  temp_value->SetBoolean("acceptSslCerts", false);
+  // Even when ChromeDriver does not OS-events, the input simulation produces
+  // the same effect for most purposes (except IME).
+  temp_value->SetBoolean("nativeEvents", true);
 
   // Custom non-standard session info.
   temp_value->SetWithoutPathExpansion(
diff --git a/chrome/test/webdriver/webdriver_capabilities_parser.cc b/chrome/test/webdriver/webdriver_capabilities_parser.cc
new file mode 100644
index 0000000..fabdd4a
--- /dev/null
+++ b/chrome/test/webdriver/webdriver_capabilities_parser.cc
@@ -0,0 +1,240 @@
+// Copyright (c) 2011 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.
+
+#include "chrome/test/webdriver/webdriver_capabilities_parser.h"
+
+#include "base/base64.h"
+#include "base/file_util.h"
+#include "base/format_macros.h"
+#include "base/logging.h"
+#include "base/stringprintf.h"
+#include "base/values.h"
+#include "chrome/common/zip.h"
+#include "chrome/test/webdriver/webdriver_error.h"
+#include "chrome/test/webdriver/webdriver_util.h"
+
+using base::Value;
+
+namespace webdriver {
+
+namespace {
+
+Error* CreateBadInputError(const std::string& name,
+                           Value::Type type,
+                           const Value* option) {
+  return new Error(kBadRequest, base::StringPrintf(
+      "%s must be of type %s, not %s. Received: %s",
+      name.c_str(), GetJsonTypeName(type),
+      GetJsonTypeName(option->GetType()),
+      JsonStringifyForDisplay(option).c_str()));
+}
+
+}  // namespace
+
+Capabilities::Capabilities()
+    : command(CommandLine::NO_PROGRAM),
+      detach(false),
+      load_async(false),
+      native_events(false),
+      verbose(false) { }
+
+Capabilities::~Capabilities() { }
+
+CapabilitiesParser::CapabilitiesParser(
+    const base::DictionaryValue* capabilities_dict,
+    const FilePath& root_path,
+    Capabilities* capabilities)
+    : dict_(capabilities_dict),
+      root_(root_path),
+      caps_(capabilities) {
+}
+
+CapabilitiesParser::~CapabilitiesParser() { }
+
+Error* CapabilitiesParser::Parse() {
+  const char kOptionsKey[] = "chromeOptions";
+  const base::DictionaryValue* options = dict_;
+  bool legacy_options = true;
+  Value* options_value;
+  if (dict_->Get(kOptionsKey, &options_value)) {
+    legacy_options = false;
+    if (options_value->IsType(Value::TYPE_DICTIONARY)) {
+      options = static_cast<DictionaryValue*>(options_value);
+    } else {
+      return CreateBadInputError(
+          kOptionsKey, Value::TYPE_DICTIONARY, options_value);
+    }
+  }
+
+  typedef Error* (CapabilitiesParser::*Parser)(const Value*);
+  std::map<std::string, Parser> parser_map;
+  if (legacy_options) {
+    parser_map["chrome.binary"] = &CapabilitiesParser::ParseBinary;
+    parser_map["chrome.channel"] = &CapabilitiesParser::ParseChannel;
+    parser_map["chrome.detach"] = &CapabilitiesParser::ParseDetach;
+    parser_map["chrome.extensions"] = &CapabilitiesParser::ParseExtensions;
+    parser_map["chrome.loadAsync"] = &CapabilitiesParser::ParseLoadAsync;
+    parser_map["chrome.nativeEvents"] = &CapabilitiesParser::ParseNativeEvents;
+    parser_map["chrome.profile"] = &CapabilitiesParser::ParseProfile;
+    parser_map["chrome.switches"] = &CapabilitiesParser::ParseArgs;
+    parser_map["chrome.verbose"] = &CapabilitiesParser::ParseVerbose;
+  } else {
+    parser_map["args"] = &CapabilitiesParser::ParseArgs;
+    parser_map["binary"] = &CapabilitiesParser::ParseBinary;
+    parser_map["channel"] = &CapabilitiesParser::ParseChannel;
+    parser_map["detach"] = &CapabilitiesParser::ParseDetach;
+    parser_map["extensions"] = &CapabilitiesParser::ParseExtensions;
+    parser_map["loadAsync"] = &CapabilitiesParser::ParseLoadAsync;
+    parser_map["nativeEvents"] = &CapabilitiesParser::ParseNativeEvents;
+    parser_map["profile"] = &CapabilitiesParser::ParseProfile;
+    parser_map["verbose"] = &CapabilitiesParser::ParseVerbose;
+  }
+
+  base::DictionaryValue::key_iterator key_iter = options->begin_keys();
+  for (; key_iter != options->end_keys(); ++key_iter) {
+    if (parser_map.find(*key_iter) == parser_map.end()) {
+      LOG(WARNING) << "Ignoring unrecognized capability: " << *key_iter;
+      continue;
+    }
+    Value* option = NULL;
+    options->GetWithoutPathExpansion(*key_iter, &option);
+    Error* error = (this->*parser_map[*key_iter])(option);
+    if (error) {
+      error->AddDetails(base::StringPrintf(
+          "Error occurred while processing capability '%s'",
+          (*key_iter).c_str()));
+      return error;
+    }
+  }
+  return NULL;
+}
+
+Error* CapabilitiesParser::ParseArgs(const Value* option) {
+  const base::ListValue* args;
+  if (!option->GetAsList(&args))
+    return CreateBadInputError("arguments", Value::TYPE_LIST, option);
+  for (size_t i = 0; i < args->GetSize(); ++i) {
+    std::string arg_string;
+    if (!args->GetString(i, &arg_string))
+      return CreateBadInputError("argument", Value::TYPE_STRING, option);
+    size_t separator_index = arg_string.find("=");
+    if (separator_index != std::string::npos) {
+      CommandLine::StringType arg_string_native;
+      if (!args->GetString(i, &arg_string_native))
+        return CreateBadInputError("argument", Value::TYPE_STRING, option);
+      caps_->command.AppendSwitchNative(
+          arg_string.substr(0, separator_index),
+          arg_string_native.substr(separator_index + 1));
+    } else {
+      caps_->command.AppendSwitch(arg_string);
+    }
+  }
+  return NULL;
+}
+
+Error* CapabilitiesParser::ParseBinary(const Value* option) {
+  FilePath::StringType path;
+  if (!option->GetAsString(&path)) {
+    return CreateBadInputError("binary path", Value::TYPE_STRING, option);
+  }
+  caps_->command.SetProgram(FilePath(path));
+  return NULL;
+}
+
+Error* CapabilitiesParser::ParseChannel(const Value* option) {
+  if (!option->GetAsString(&caps_->channel))
+    return CreateBadInputError("channel", Value::TYPE_STRING, option);
+  return NULL;
+}
+
+Error* CapabilitiesParser::ParseDetach(const Value* option) {
+  if (!option->GetAsBoolean(&caps_->detach))
+    return CreateBadInputError("detach", Value::TYPE_BOOLEAN, option);
+  return NULL;
+}
+
+Error* CapabilitiesParser::ParseExtensions(const Value* option) {
+  const base::ListValue* extensions;
+  if (!option->GetAsList(&extensions))
+    return CreateBadInputError("extensions", Value::TYPE_LIST, option);
+  for (size_t i = 0; i < extensions->GetSize(); ++i) {
+    std::string extension_base64;
+    if (!extensions->GetString(i, &extension_base64)) {
+      return new Error(kBadRequest,
+                       "Each extension must be a base64 encoded string");
+    }
+    FilePath extension = root_.AppendASCII(
+        base::StringPrintf("extension%" PRIuS ".crx", i));
+    std::string error_msg;
+    if (!DecodeAndWriteFile(extension, extension_base64, false /* unzip */,
+                            &error_msg)) {
+      return new Error(
+          kUnknownError,
+          "Error occurred while parsing extension: " + error_msg);
+    }
+    caps_->extensions.push_back(extension);
+  }
+  return NULL;
+}
+
+Error* CapabilitiesParser::ParseLoadAsync(const Value* option) {
+  if (!option->GetAsBoolean(&caps_->load_async))
+    return CreateBadInputError("loadAsync", Value::TYPE_BOOLEAN, option);
+  return NULL;
+}
+
+Error* CapabilitiesParser::ParseNativeEvents(const Value* option) {
+  if (!option->GetAsBoolean(&caps_->native_events))
+    return CreateBadInputError("nativeEvents", Value::TYPE_BOOLEAN, option);
+  return NULL;
+}
+
+Error* CapabilitiesParser::ParseProfile(const Value* option) {
+  std::string profile_base64;
+  if (!option->GetAsString(&profile_base64))
+    return CreateBadInputError("profile", Value::TYPE_STRING, option);
+  std::string error_msg;
+  caps_->profile = root_.AppendASCII("profile");
+  if (!DecodeAndWriteFile(caps_->profile, profile_base64, true /* unzip */,
+                          &error_msg))
+    return new Error(kUnknownError, "unable to unpack profile: " + error_msg);
+  return NULL;
+}
+
+Error* CapabilitiesParser::ParseVerbose(const Value* option) {
+  if (!option->GetAsBoolean(&caps_->verbose))
+    return CreateBadInputError("verbose", Value::TYPE_BOOLEAN, option);
+  return NULL;
+}
+
+bool CapabilitiesParser::DecodeAndWriteFile(
+    const FilePath& path,
+    const std::string& base64,
+    bool unzip,
+    std::string* error_msg) {
+  std::string data;
+  if (!base::Base64Decode(base64, &data)) {
+    *error_msg = "Could not decode base64 data";
+    return false;
+  }
+  if (unzip) {
+    FilePath temp_file(root_.AppendASCII(GenerateRandomID()));
+    if (!file_util::WriteFile(temp_file, data.c_str(), data.length())) {
+      *error_msg = "Could not write file";
+      return false;
+    }
+    if (!zip::Unzip(temp_file, path)) {
+      *error_msg = "Could not unzip archive";
+      return false;
+    }
+  } else {
+    if (!file_util::WriteFile(path, data.c_str(), data.length())) {
+      *error_msg = "Could not write file";
+      return false;
+    }
+  }
+  return true;
+}
+
+}  // namespace webdriver
diff --git a/chrome/test/webdriver/webdriver_capabilities_parser.h b/chrome/test/webdriver/webdriver_capabilities_parser.h
new file mode 100644
index 0000000..8f9320d
--- /dev/null
+++ b/chrome/test/webdriver/webdriver_capabilities_parser.h
@@ -0,0 +1,109 @@
+// Copyright (c) 2011 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.
+
+#ifndef CHROME_TEST_WEBDRIVER_WEBDRIVER_CAPABILITIES_PARSER_H_
+#define CHROME_TEST_WEBDRIVER_WEBDRIVER_CAPABILITIES_PARSER_H_
+#pragma once
+
+#include <string>
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/command_line.h"
+#include "base/file_path.h"
+
+namespace base {
+class DictionaryValue;
+class Value;
+}
+
+namespace webdriver {
+
+class Error;
+
+// Contains all the capabilities that a user may request when starting a
+// new session.
+struct Capabilities {
+  Capabilities();
+  ~Capabilities();
+
+  // Command line to use for starting Chrome.
+  CommandLine command;
+
+  // Channel ID to use for connecting to an already running Chrome.
+  std::string channel;
+
+  // Whether the lifetime of the started Chrome browser process should be
+  // bound to ChromeDriver's process. If true, Chrome will not quit if
+  // ChromeDriver dies.
+  bool detach;
+
+  // List of paths for extensions to install on startup.
+  std::vector<FilePath> extensions;
+
+  // Whether Chrome should not block when loading.
+  bool load_async;
+
+  // Whether Chrome should simulate input events using OS APIs instead of
+  // WebKit APIs.
+  bool native_events;
+
+  // Path to a custom profile to use.
+  FilePath profile;
+
+  // Whether ChromeDriver should log verbosely.
+  bool verbose;
+};
+
+// Parses the given capabilities dictionary to produce a |Capabilities|
+// instance.
+// See webdriver's desired capabilities for more info.
+class CapabilitiesParser {
+ public:
+  // Create a new parser. |capabilities_dict| is the dictionary for all
+  // of the user's desired capabilities. |root_path| is the root directory
+  // to use for writing any necessary files to disk. This function will not
+  // create it or delete it. All files written to disk will be placed in
+  // this directory.
+  CapabilitiesParser(const base::DictionaryValue* capabilities_dict,
+                     const FilePath& root_path,
+                     Capabilities* capabilities);
+  ~CapabilitiesParser();
+
+  // Parses the capabilities. May return an error.
+  Error* Parse();
+
+ private:
+  Error* ParseArgs(const base::Value* option);
+  Error* ParseBinary(const base::Value* option);
+  Error* ParseChannel(const base::Value* option);
+  Error* ParseDetach(const base::Value* option);
+  Error* ParseExtensions(const base::Value* option);
+  Error* ParseLoadAsync(const base::Value* option);
+  Error* ParseNativeEvents(const base::Value* option);
+  Error* ParseProfile(const base::Value* option);
+  Error* ParseVerbose(const base::Value* option);
+  // Decodes the given base64-encoded string, optionally unzips it, and
+  // writes the result to |path|.
+  // On error, false will be returned and |error_msg| will be set.
+  bool DecodeAndWriteFile(const FilePath& path,
+                          const std::string& base64,
+                          bool unzip,
+                          std::string* error_msg);
+
+  // The capabilities dictionary to parse.
+  const base::DictionaryValue* dict_;
+
+  // The root directory under which to write all files.
+  const FilePath root_;
+
+  // A pointer to the capabilities to modify while parsing.
+  Capabilities* caps_;
+
+  DISALLOW_COPY_AND_ASSIGN(CapabilitiesParser);
+};
+
+}  // namespace webdriver
+
+#endif  // CHROME_TEST_WEBDRIVER_WEBDRIVER_CAPABILITIES_PARSER_H_
diff --git a/chrome/test/webdriver/webdriver_capabilities_parser_unittest.cc b/chrome/test/webdriver/webdriver_capabilities_parser_unittest.cc
new file mode 100644
index 0000000..f3123c3
--- /dev/null
+++ b/chrome/test/webdriver/webdriver_capabilities_parser_unittest.cc
@@ -0,0 +1,141 @@
+// Copyright (c) 2011 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.
+
+#include "base/base64.h"
+#include "base/file_path.h"
+#include "base/file_util.h"
+#include "base/scoped_temp_dir.h"
+#include "base/values.h"
+#include "chrome/common/zip.h"
+#include "chrome/test/webdriver/webdriver_capabilities_parser.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+using base::DictionaryValue;
+using base::ListValue;
+using base::Value;
+
+namespace webdriver {
+
+TEST(CapabilitiesParser, NoCaps) {
+  Capabilities caps;
+  DictionaryValue dict;
+  CapabilitiesParser parser(&dict, FilePath(), &caps);
+  ASSERT_FALSE(parser.Parse());
+}
+
+TEST(CapabilitiesParser, SimpleCaps) {
+  DictionaryValue dict;
+  DictionaryValue* options = new DictionaryValue();
+  dict.Set("chromeOptions", options);
+
+  options->SetString("binary", "binary");
+  options->SetString("channel", "channel");
+  options->SetBoolean("detach", true);
+  options->SetBoolean("loadAsync", true);
+  options->SetBoolean("nativeEvents", true);
+  options->SetBoolean("verbose", true);
+
+  Capabilities caps;
+  ScopedTempDir temp_dir;
+  ASSERT_TRUE(temp_dir.CreateUniqueTempDir());
+  CapabilitiesParser parser(&dict, temp_dir.path(), &caps);
+  ASSERT_FALSE(parser.Parse());
+  EXPECT_EQ(FILE_PATH_LITERAL("binary"), caps.command.GetProgram().value());
+  EXPECT_STREQ("channel", caps.channel.c_str());
+  EXPECT_TRUE(caps.detach);
+  EXPECT_TRUE(caps.load_async);
+  EXPECT_TRUE(caps.native_events);
+  EXPECT_TRUE(caps.verbose);
+}
+
+TEST(CapabilitiesParser, Args) {
+  DictionaryValue dict;
+  DictionaryValue* options = new DictionaryValue();
+  dict.Set("chromeOptions", options);
+
+  ListValue* args = new ListValue();
+  args->Append(Value::CreateStringValue("arg1"));
+  args->Append(Value::CreateStringValue("arg2=val"));
+  args->Append(Value::CreateStringValue("arg3='a space'"));
+  options->Set("args", args);
+
+  Capabilities caps;
+  ScopedTempDir temp_dir;
+  ASSERT_TRUE(temp_dir.CreateUniqueTempDir());
+  CapabilitiesParser parser(&dict, temp_dir.path(), &caps);
+  ASSERT_FALSE(parser.Parse());
+  EXPECT_TRUE(caps.command.HasSwitch("arg1"));
+  EXPECT_STREQ("val", caps.command.GetSwitchValueASCII("arg2").c_str());
+  EXPECT_STREQ("'a space'", caps.command.GetSwitchValueASCII("arg3").c_str());
+}
+
+TEST(CapabilitiesParser, Extensions) {
+  DictionaryValue dict;
+  DictionaryValue* options = new DictionaryValue();
+  dict.Set("chromeOptions", options);
+
+  ListValue* extensions = new ListValue();
+  extensions->Append(Value::CreateStringValue("TWFu"));
+  extensions->Append(Value::CreateStringValue("TWFuTWFu"));
+  options->Set("extensions", extensions);
+
+  Capabilities caps;
+  ScopedTempDir temp_dir;
+  ASSERT_TRUE(temp_dir.CreateUniqueTempDir());
+  CapabilitiesParser parser(&dict, temp_dir.path(), &caps);
+  ASSERT_FALSE(parser.Parse());
+  ASSERT_EQ(2u, caps.extensions.size());
+  std::string contents;
+  ASSERT_TRUE(file_util::ReadFileToString(caps.extensions[0], &contents));
+  EXPECT_STREQ("Man", contents.c_str());
+  contents.clear();
+  ASSERT_TRUE(file_util::ReadFileToString(caps.extensions[1], &contents));
+  EXPECT_STREQ("ManMan", contents.c_str());
+}
+
+TEST(CapabilitiesParser, Profile) {
+  DictionaryValue dict;
+  DictionaryValue* options = new DictionaryValue();
+  dict.Set("chromeOptions", options);
+
+  ScopedTempDir temp_dir;
+  ASSERT_TRUE(temp_dir.CreateUniqueTempDir());
+  FilePath folder = temp_dir.path().AppendASCII("folder");
+  ASSERT_TRUE(file_util::CreateDirectory(folder));
+  ASSERT_EQ(4, file_util::WriteFile(
+      folder.AppendASCII("data"), "data", 4));
+  FilePath zip = temp_dir.path().AppendASCII("data.zip");
+  ASSERT_TRUE(zip::Zip(folder, zip, false /* include_hidden_files */));
+  std::string contents;
+  ASSERT_TRUE(file_util::ReadFileToString(zip, &contents));
+  std::string base64;
+  ASSERT_TRUE(base::Base64Encode(contents, &base64));
+  options->SetString("profile", base64);
+
+  Capabilities caps;
+  CapabilitiesParser parser(&dict, temp_dir.path(), &caps);
+  ASSERT_FALSE(parser.Parse());
+  std::string new_contents;
+  ASSERT_TRUE(file_util::ReadFileToString(
+      caps.profile.AppendASCII("data"), &new_contents));
+  EXPECT_STREQ("data", new_contents.c_str());
+}
+
+TEST(CapabilitiesParser, UnknownCap) {
+  Capabilities caps;
+  DictionaryValue dict;
+  dict.SetString("chromeOptions.nosuchcap", "none");
+  CapabilitiesParser parser(&dict, FilePath(), &caps);
+  ASSERT_FALSE(parser.Parse());
+}
+
+TEST(CapabilitiesParser, BadInput) {
+  Capabilities caps;
+  DictionaryValue dict;
+  dict.SetString("chromeOptions.verbose", "false");
+  CapabilitiesParser parser(&dict, FilePath(), &caps);
+  ASSERT_TRUE(parser.Parse());
+}
+
+}  // namespace webdriver
diff --git a/chrome/test/webdriver/webdriver_util.cc b/chrome/test/webdriver/webdriver_util.cc
index 45e080f..5440d5a 100644
--- a/chrome/test/webdriver/webdriver_util.cc
+++ b/chrome/test/webdriver/webdriver_util.cc
@@ -7,9 +7,13 @@
 #include "base/basictypes.h"
 #include "base/format_macros.h"
 #include "base/json/json_writer.h"
+#include "base/memory/scoped_ptr.h"
 #include "base/rand_util.h"
 #include "base/stringprintf.h"
-#include "base/values.h"
+
+using base::DictionaryValue;
+using base::ListValue;
+using base::Value;
 
 namespace webdriver {
 
@@ -27,6 +31,91 @@ std::string JsonStringify(const Value* value) {
   return json;
 }
 
+namespace {
+
+// Truncates the given string to 40 characters, adding an ellipsis if
+// truncation was necessary.
+void TruncateString(std::string* data) {
+  if (data->length() > 40) {
+    data->resize(40);
+    data->replace(37, 3, "...");
+  }
+}
+
+// Truncates all strings contained in the given value.
+void TruncateContainedStrings(Value* value) {
+  ListValue* list;
+  if (value->IsType(Value::TYPE_DICTIONARY)) {
+    DictionaryValue* dict = static_cast<DictionaryValue*>(value);
+    DictionaryValue::key_iterator key = dict->begin_keys();
+    for (; key != dict->end_keys(); ++key) {
+      Value* child;
+      if (!dict->GetWithoutPathExpansion(*key, &child))
+        continue;
+      std::string data;
+      if (child->GetAsString(&data)) {
+        TruncateString(&data);
+        dict->SetWithoutPathExpansion(*key, Value::CreateStringValue(data));
+      } else {
+        TruncateContainedStrings(child);
+      }
+    }
+  } else if (value->GetAsList(&list)) {
+    for (size_t i = 0; i < list->GetSize(); ++i) {
+      Value* child;
+      if (!list->Get(i, &child))
+        continue;
+      std::string data;
+      if (child->GetAsString(&data)) {
+        TruncateString(&data);
+        list->Set(i, Value::CreateStringValue(data));
+      } else {
+        TruncateContainedStrings(child);
+      }
+    }
+  }
+}
+
+}  // namespace
+
+std::string JsonStringifyForDisplay(const Value* value) {
+  scoped_ptr<Value> copy;
+  if (value->IsType(Value::TYPE_STRING)) {
+    std::string data;
+    value->GetAsString(&data);
+    TruncateString(&data);
+    copy.reset(Value::CreateStringValue(data));
+  } else {
+    copy.reset(value->DeepCopy());
+    TruncateContainedStrings(copy.get());
+  }
+  std::string json;
+  base::JSONWriter::Write(copy.get(), true /* pretty_print */, &json);
+  return json;
+}
+
+const char* GetJsonTypeName(Value::Type type) {
+  switch (type) {
+    case Value::TYPE_NULL:
+      return "null";
+    case Value::TYPE_BOOLEAN:
+      return "boolean";
+    case Value::TYPE_INTEGER:
+      return "integer";
+    case Value::TYPE_DOUBLE:
+      return "double";
+    case Value::TYPE_STRING:
+      return "string";
+    case Value::TYPE_BINARY:
+      return "binary";
+    case Value::TYPE_DICTIONARY:
+      return "dictionary";
+    case Value::TYPE_LIST:
+      return "list";
+  }
+  return "unknown";
+}
+
 ValueParser::ValueParser() { }
 
 ValueParser::~ValueParser() { }
@@ -34,11 +123,11 @@ ValueParser::~ValueParser() { }
 }  // namespace webdriver
 
 bool ValueConversionTraits<webdriver::SkipParsing>::SetFromValue(
-    const base::Value* value, const webdriver::SkipParsing* t) {
+    const Value* value, const webdriver::SkipParsing* t) {
   return true;
 }
 
 bool ValueConversionTraits<webdriver::SkipParsing>::CanConvert(
-    const base::Value* value) {
+    const Value* value) {
   return true;
 }
diff --git a/chrome/test/webdriver/webdriver_util.h b/chrome/test/webdriver/webdriver_util.h
index e36bdb7..c512ba5 100644
--- a/chrome/test/webdriver/webdriver_util.h
+++ b/chrome/test/webdriver/webdriver_util.h
@@ -11,14 +11,11 @@
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
+#include "base/values.h"
 #include "chrome/test/automation/value_conversion_traits.h"
 
 class FilePath;
 
-namespace base {
-class Value;
-}
-
 namespace webdriver {
 
 // Generates a random, 32-character hexidecimal ID.
@@ -27,6 +24,13 @@ std::string GenerateRandomID();
 // Returns the equivalent JSON string for the given value.
 std::string JsonStringify(const base::Value* value);
 
+// Returns the JSON string for the given value, with the exception that
+// long strings are shortened for easier display.
+std::string JsonStringifyForDisplay(const base::Value* value);
+
+// Returns the string representation of the given type, for display purposes.
+const char* GetJsonTypeName(base::Value::Type type);
+
 #if defined(OS_MACOSX)
 // Gets the paths to the user and local application directory.
 void GetApplicationDirs(std::vector<FilePath>* app_dirs);