[chromedriver] Implement connecting to devtools and loading a page.

BUG=none


Review URL: https://chromiumcodereview.appspot.com/11415205

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@171035 0039d316-1c4b-4281-b951-d872f2087c98

25 files changed, 610 insertions, 27 deletions

diff --git a/chrome/test/chromedriver/chrome.h b/chrome/test/chromedriver/chrome.h
index c3df4c4..a0675d0 100644
--- a/chrome/test/chromedriver/chrome.h
+++ b/chrome/test/chromedriver/chrome.h
@@ -5,11 +5,15 @@
 #ifndef CHROME_TEST_CHROMEDRIVER_CHROME_H_
 #define CHROME_TEST_CHROMEDRIVER_CHROME_H_
 
+#include <string>
+
 class Status;
 
 class Chrome {
  public:
   virtual ~Chrome() {}
+
+  virtual Status Load(const std::string& url) = 0;
   virtual Status Quit() = 0;
 };
 
diff --git a/chrome/test/chromedriver/chrome_impl.cc b/chrome/test/chromedriver/chrome_impl.cc
index 5cac6f3..f074d3c 100644
--- a/chrome/test/chromedriver/chrome_impl.cc
+++ b/chrome/test/chromedriver/chrome_impl.cc
@@ -4,13 +4,42 @@
 
 #include "chrome/test/chromedriver/chrome_impl.h"
 
+#include "base/json/json_reader.h"
+#include "base/json/json_writer.h"
 #include "base/logging.h"
 #include "base/process_util.h"
+#include "base/stringprintf.h"
+#include "base/threading/platform_thread.h"
+#include "base/time.h"
+#include "base/values.h"
+#include "chrome/test/chromedriver/devtools_client.h"
+#include "chrome/test/chromedriver/net/net_util.h"
+#include "chrome/test/chromedriver/net/url_request_context_getter.h"
 #include "chrome/test/chromedriver/status.h"
+#include "googleurl/src/gurl.h"
+
+namespace {
+
+Status FetchPagesInfo(URLRequestContextGetter* context_getter,
+                      int port,
+                      std::list<std::string>* debugger_urls) {
+  std::string url = base::StringPrintf(
+      "http://127.0.0.1:%d/json", port);
+  std::string data;
+  if (!FetchUrl(GURL(url), context_getter, &data))
+    return Status(kChromeNotReachable);
+  return internal::ParsePagesInfo(data, debugger_urls);
+}
+
+}  // namespace
 
 ChromeImpl::ChromeImpl(base::ProcessHandle process,
-                       base::ScopedTempDir* user_data_dir)
-    : process_(process) {
+                       URLRequestContextGetter* context_getter,
+                       base::ScopedTempDir* user_data_dir,
+                       int port)
+    : process_(process),
+      context_getter_(context_getter),
+      port_(port) {
   if (user_data_dir->IsValid()) {
     CHECK(user_data_dir_.Set(user_data_dir->Take()));
   }
@@ -20,8 +49,57 @@ ChromeImpl::~ChromeImpl() {
   base::CloseProcessHandle(process_);
 }
 
+Status ChromeImpl::Init() {
+  base::Time deadline = base::Time::Now() + base::TimeDelta::FromSeconds(20);
+  std::list<std::string> debugger_urls;
+  while (base::Time::Now() < deadline) {
+    FetchPagesInfo(context_getter_, port_, &debugger_urls);
+    if (debugger_urls.empty())
+      base::PlatformThread::Sleep(base::TimeDelta::FromMilliseconds(100));
+    else
+      break;
+  }
+  if (debugger_urls.empty())
+    return Status(kUnknownError, "unable to discover open pages");
+  client_.reset(new DevToolsClient(context_getter_, debugger_urls.front()));
+  return Status(kOk);
+}
+
+Status ChromeImpl::Load(const std::string& url) {
+  base::DictionaryValue params;
+  params.SetString("url", url);
+  return client_->SendCommand("Page.navigate", params);
+}
+
 Status ChromeImpl::Quit() {
   if (!base::KillProcess(process_, 0, true))
     return Status(kUnknownError, "cannot kill Chrome");
   return Status(kOk);
 }
+
+namespace internal {
+
+Status ParsePagesInfo(const std::string& data,
+                      std::list<std::string>* debugger_urls) {
+  scoped_ptr<base::Value> value(base::JSONReader::Read(data));
+  if (!value.get())
+    return Status(kUnknownError, "DevTools returned invalid JSON");
+  base::ListValue* list;
+  if (!value->GetAsList(&list))
+    return Status(kUnknownError, "DevTools did not return list");
+
+  std::list<std::string> internal_urls;
+  for (size_t i = 0; i < list->GetSize(); ++i) {
+    base::DictionaryValue* info;
+    if (!list->GetDictionary(i, &info))
+      return Status(kUnknownError, "DevTools contains non-dictionary item");
+    std::string debugger_url;
+    if (!info->GetString("webSocketDebuggerUrl", &debugger_url))
+      return Status(kUnknownError, "DevTools did not include debugger URL");
+    internal_urls.push_back(debugger_url);
+  }
+  debugger_urls->swap(internal_urls);
+  return Status(kOk);
+}
+
+}  // namespace internal
diff --git a/chrome/test/chromedriver/chrome_impl.h b/chrome/test/chromedriver/chrome_impl.h
index 1a6d1c8..5f6056e 100644
--- a/chrome/test/chromedriver/chrome_impl.h
+++ b/chrome/test/chromedriver/chrome_impl.h
@@ -5,24 +5,47 @@
 #ifndef CHROME_TEST_CHROMEDRIVER_CHROME_IMPL_H_
 #define CHROME_TEST_CHROMEDRIVER_CHROME_IMPL_H_
 
+#include <list>
+#include <string>
+
 #include "base/compiler_specific.h"
 #include "base/files/scoped_temp_dir.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
 #include "base/process.h"
 #include "chrome/test/chromedriver/chrome.h"
 
+class DevToolsClient;
 class Status;
+class URLRequestContextGetter;
 
 class ChromeImpl : public Chrome {
  public:
-  ChromeImpl(base::ProcessHandle process, base::ScopedTempDir* user_data_dir);
+  ChromeImpl(base::ProcessHandle process,
+             URLRequestContextGetter* context_getter,
+             base::ScopedTempDir* user_data_dir,
+             int port);
   virtual ~ChromeImpl();
 
+  Status Init();
+
   // Overridden from Chrome:
+  virtual Status Load(const std::string& url) OVERRIDE;
   virtual Status Quit() OVERRIDE;
 
  private:
   base::ProcessHandle process_;
+  scoped_refptr<URLRequestContextGetter> context_getter_;
   base::ScopedTempDir user_data_dir_;
+  int port_;
+  scoped_ptr<DevToolsClient> client_;
 };
 
+namespace internal {
+
+Status ParsePagesInfo(const std::string& data,
+                      std::list<std::string>* debugger_urls);
+
+}  // namespace internal
+
 #endif  // CHROME_TEST_CHROMEDRIVER_CHROME_IMPL_H_
diff --git a/chrome/test/chromedriver/chrome_impl_unittest.cc b/chrome/test/chromedriver/chrome_impl_unittest.cc
new file mode 100644
index 0000000..70f0ea4
--- /dev/null
+++ b/chrome/test/chromedriver/chrome_impl_unittest.cc
@@ -0,0 +1,63 @@
+// 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.
+
+#include <list>
+#include <string>
+
+#include "chrome/test/chromedriver/chrome_impl.h"
+#include "chrome/test/chromedriver/status.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+TEST(ParsePagesInfo, Normal) {
+  std::list<std::string> urls;
+  Status status = internal::ParsePagesInfo(
+      "[{\"webSocketDebuggerUrl\": \"http://debugurl\"}]",
+      &urls);
+  ASSERT_TRUE(status.IsOk());
+  ASSERT_EQ(1u, urls.size());
+  ASSERT_EQ("http://debugurl", urls.front());
+}
+
+TEST(ParsePagesInfo, Multiple) {
+  std::list<std::string> urls;
+  Status status = internal::ParsePagesInfo(
+      "[{\"webSocketDebuggerUrl\": \"http://debugurl\"},"
+      " {\"webSocketDebuggerUrl\": \"http://debugurl2\"}]",
+      &urls);
+  ASSERT_TRUE(status.IsOk());
+  ASSERT_EQ(2u, urls.size());
+  ASSERT_EQ("http://debugurl", urls.front());
+  ASSERT_EQ("http://debugurl2", urls.back());
+}
+
+namespace {
+
+void AssertFails(const std::string& data) {
+  std::list<std::string> urls;
+  Status status = internal::ParsePagesInfo(data, &urls);
+  ASSERT_FALSE(status.IsOk());
+  ASSERT_EQ(0u, urls.size());
+}
+
+}  // namespace
+
+TEST(ParsePagesInfo, InvalidJSON) {
+  AssertFails("[");
+}
+
+TEST(ParsePagesInfo, NonList) {
+  AssertFails("{}");
+}
+
+TEST(ParsePagesInfo, NonDictionary) {
+  AssertFails("[1]");
+}
+
+TEST(ParsePagesInfo, NoDebuggerUrl) {
+  AssertFails("[{\"hi\": 1}]");
+}
+
+TEST(ParsePagesInfo, InvalidDebuggerUrl) {
+  AssertFails("[{\"webSocketDebuggerUrl\": 1}]");
+}
diff --git a/chrome/test/chromedriver/chrome_launcher_impl.cc b/chrome/test/chromedriver/chrome_launcher_impl.cc
index 3e124fb..ee484ab 100644
--- a/chrome/test/chromedriver/chrome_launcher_impl.cc
+++ b/chrome/test/chromedriver/chrome_launcher_impl.cc
@@ -10,12 +10,15 @@
 #include "base/file_path.h"
 #include "base/process.h"
 #include "base/process_util.h"
+#include "base/string_number_conversions.h"
 #include "chrome/test/chromedriver/chrome.h"
 #include "chrome/test/chromedriver/chrome_finder.h"
 #include "chrome/test/chromedriver/chrome_impl.h"
+#include "chrome/test/chromedriver/net/url_request_context_getter.h"
 #include "chrome/test/chromedriver/status.h"
 
-ChromeLauncherImpl::ChromeLauncherImpl() {}
+ChromeLauncherImpl::ChromeLauncherImpl(URLRequestContextGetter* context_getter)
+    : context_getter_(context_getter) {}
 
 ChromeLauncherImpl::~ChromeLauncherImpl() {}
 
@@ -28,7 +31,10 @@ Status ChromeLauncherImpl::Launch(
       return Status(kUnknownError, "cannot find Chrome binary");
   }
 
+  int port = 33081;
   CommandLine command(program);
+  command.AppendSwitchASCII("remote-debugging-port", base::IntToString(port));
+  command.AppendSwitch("no-first-run");
   command.AppendSwitch("enable-logging");
   command.AppendSwitchASCII("logging-level", "1");
   base::ScopedTempDir user_data_dir;
@@ -41,7 +47,11 @@ Status ChromeLauncherImpl::Launch(
   base::ProcessHandle process;
   if (!base::LaunchProcess(command, options, &process))
     return Status(kUnknownError, "chrome failed to start");
-  chrome->reset(new ChromeImpl(process, &user_data_dir));
-
+  scoped_ptr<ChromeImpl> chrome_impl(new ChromeImpl(
+      process, context_getter_, &user_data_dir, port));
+  Status status = chrome_impl->Init();
+  if (status.IsError())
+    return status;
+  chrome->reset(chrome_impl.release());
   return Status(kOk);
 }
diff --git a/chrome/test/chromedriver/chrome_launcher_impl.h b/chrome/test/chromedriver/chrome_launcher_impl.h
index ecd7bd1..542017e3b 100644
--- a/chrome/test/chromedriver/chrome_launcher_impl.h
+++ b/chrome/test/chromedriver/chrome_launcher_impl.h
@@ -7,16 +7,18 @@
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
+#include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "chrome/test/chromedriver/chrome_launcher.h"
 
 class Chrome;
 class FilePath;
 class Status;
+class URLRequestContextGetter;
 
 class ChromeLauncherImpl : public ChromeLauncher {
  public:
-  ChromeLauncherImpl();
+  explicit ChromeLauncherImpl(URLRequestContextGetter* context_getter);
   virtual ~ChromeLauncherImpl();
 
   // Overridden from ChromeLauncher:
@@ -24,6 +26,8 @@ class ChromeLauncherImpl : public ChromeLauncher {
                         scoped_ptr<Chrome>* chrome) OVERRIDE;
 
  private:
+  scoped_refptr<URLRequestContextGetter> context_getter_;
+
   DISALLOW_COPY_AND_ASSIGN(ChromeLauncherImpl);
 };
 
diff --git a/chrome/test/chromedriver/chromedriver.cc b/chrome/test/chromedriver/chromedriver.cc
index 9f66847..70b5746 100644
--- a/chrome/test/chromedriver/chromedriver.cc
+++ b/chrome/test/chromedriver/chromedriver.cc
@@ -6,14 +6,19 @@
 
 #include "base/json/json_reader.h"
 #include "base/json/json_writer.h"
+#include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/synchronization/lock.h"
 #include "base/values.h"
 #include "chrome/test/chromedriver/command_executor.h"
 #include "chrome/test/chromedriver/status.h"
 
 namespace {
 
+// Guards |g_executor_initialized|.
+base::LazyInstance<base::Lock> g_lazy_lock = LAZY_INSTANCE_INITIALIZER;
+bool g_executor_initialized = false;
 CommandExecutor* g_command_executor = NULL;
 
 void SetResponse(StatusCode status,
@@ -39,10 +44,19 @@ void SetError(const std::string& error_msg,
 
 void Init(scoped_ptr<CommandExecutor> executor) {
   g_command_executor = executor.release();
+  // We do not call CommandExecutor::Init here because you can't do some things
+  // (e.g., creating threads) during DLL loading on Windows.
 }
 
 void ExecuteCommand(const std::string& command, std::string* response) {
   CHECK(g_command_executor);
+  {
+    base::AutoLock(g_lazy_lock.Get());
+    if (!g_executor_initialized) {
+      g_command_executor->Init();
+      g_executor_initialized = true;
+    }
+  }
   std::string error_msg;
   scoped_ptr<base::Value> value(base::JSONReader::ReadAndReturnError(
       command, 0, NULL, &error_msg));
diff --git a/chrome/test/chromedriver/chromedriver.h b/chrome/test/chromedriver/chromedriver.h
index 5252da1..3872b003 100644
--- a/chrome/test/chromedriver/chromedriver.h
+++ b/chrome/test/chromedriver/chromedriver.h
@@ -12,6 +12,7 @@
 class CommandExecutor;
 
 // Inits the command executor. Must be called before |ExecuteCommand|.
+// This may be called during DLL load on Windows.
 void Init(scoped_ptr<CommandExecutor> executor);
 
 // Synchronously executes the given command. Thread safe.
diff --git a/chrome/test/chromedriver/chromedriver.py b/chrome/test/chromedriver/chromedriver.py
index cbe6d3b..c0bfadd 100644
--- a/chrome/test/chromedriver/chromedriver.py
+++ b/chrome/test/chromedriver/chromedriver.py
@@ -68,6 +68,9 @@ class ChromeDriver(object):
   def _ExecuteSessionCommand(self, name, params={}):
     return self._ExecuteCommand(name, params, self._session_id)
 
+  def Load(self, url):
+    self._ExecuteSessionCommand('get', {'url': url})
+
   def Quit(self):
     """Quits the browser and ends the session."""
     self._ExecuteSessionCommand('quit')
diff --git a/chrome/test/chromedriver/chromedriver_unittest.cc b/chrome/test/chromedriver/chromedriver_unittest.cc
index 9c85383..fc8bef6 100644
--- a/chrome/test/chromedriver/chromedriver_unittest.cc
+++ b/chrome/test/chromedriver/chromedriver_unittest.cc
@@ -38,13 +38,13 @@ class DummyExecutor : public CommandExecutor {
  public:
   virtual ~DummyExecutor() {}
 
+  virtual void Init() OVERRIDE {}
   virtual void ExecuteCommand(const std::string& name,
                               const base::DictionaryValue& params,
                               const std::string& session_id,
                               StatusCode* status,
                               scoped_ptr<base::Value>* value,
-                              std::string* out_session_id) OVERRIDE {
-  }
+                              std::string* out_session_id) OVERRIDE {}
 };
 
 
@@ -80,6 +80,8 @@ class ExecutorMock : public CommandExecutor {
     EXPECT_TRUE(DidSatisfyExpectations());
   }
 
+  virtual void Init() OVERRIDE {}
+
   virtual void ExecuteCommand(const std::string& name,
                               const base::DictionaryValue& params,
                               const std::string& session_id,
diff --git a/chrome/test/chromedriver/command_executor.h b/chrome/test/chromedriver/command_executor.h
index db0b0f9..5f8e5fe 100644
--- a/chrome/test/chromedriver/command_executor.h
+++ b/chrome/test/chromedriver/command_executor.h
@@ -22,6 +22,8 @@ class CommandExecutor {
  public:
   virtual ~CommandExecutor() {}
 
+  virtual void Init() = 0;
+
   // Executes a command synchronously. This function must be thread safe.
   virtual void ExecuteCommand(const std::string& name,
                               const base::DictionaryValue& params,
diff --git a/chrome/test/chromedriver/command_executor_impl.cc b/chrome/test/chromedriver/command_executor_impl.cc
index 57c3a24..4f5b57a 100644
--- a/chrome/test/chromedriver/command_executor_impl.cc
+++ b/chrome/test/chromedriver/command_executor_impl.cc
@@ -6,14 +6,30 @@
 
 #include "base/bind.h"
 #include "base/callback.h"
+#include "base/message_loop.h"
+#include "base/message_loop_proxy.h"
 #include "base/values.h"
+#include "chrome/test/chromedriver/chrome_launcher_impl.h"
 #include "chrome/test/chromedriver/commands.h"
+#include "chrome/test/chromedriver/net/url_request_context_getter.h"
 #include "chrome/test/chromedriver/session.h"
 #include "chrome/test/chromedriver/session_command.h"
 #include "chrome/test/chromedriver/session_map.h"
 #include "chrome/test/chromedriver/status.h"
 
-CommandExecutorImpl::CommandExecutorImpl() {
+CommandExecutorImpl::CommandExecutorImpl()
+    : io_thread_("ChromeDriver IO") {}
+
+CommandExecutorImpl::~CommandExecutorImpl() {}
+
+void CommandExecutorImpl::Init() {
+  base::Thread::Options options(MessageLoop::TYPE_IO, 0);
+  CHECK(io_thread_.StartWithOptions(options));
+  context_getter_ = new URLRequestContextGetter(
+      io_thread_.message_loop_proxy());
+  launcher_.reset(new ChromeLauncherImpl(context_getter_));
+
+  // Session commands.
   base::Callback<Status(
       const SessionCommand&,
       const base::DictionaryValue&,
@@ -22,19 +38,19 @@ CommandExecutorImpl::CommandExecutorImpl() {
       std::string*)> execute_session_command = base::Bind(
           &ExecuteSessionCommand,
           &session_map_);
+  command_map_.Set("get", base::Bind(execute_session_command,
+      base::Bind(&ExecuteGet)));
   Command quit_command = base::Bind(execute_session_command,
       base::Bind(&ExecuteQuit, &session_map_));
   command_map_.Set("quit", quit_command);
 
   // Non-session commands.
   command_map_.Set("newSession",
-      base::Bind(&ExecuteNewSession, &session_map_, &launcher_));
+      base::Bind(&ExecuteNewSession, &session_map_, launcher_.get()));
   command_map_.Set("quitAll",
       base::Bind(&ExecuteQuitAll, quit_command, &session_map_));
 }
 
-CommandExecutorImpl::~CommandExecutorImpl() {}
-
 void CommandExecutorImpl::ExecuteCommand(
     const std::string& name,
     const base::DictionaryValue& params,
diff --git a/chrome/test/chromedriver/command_executor_impl.h b/chrome/test/chromedriver/command_executor_impl.h
index 125b1e3..092809f 100644
--- a/chrome/test/chromedriver/command_executor_impl.h
+++ b/chrome/test/chromedriver/command_executor_impl.h
@@ -12,7 +12,7 @@
 #include "base/compiler_specific.h"
 #include "base/gtest_prod_util.h"
 #include "base/memory/scoped_ptr.h"
-#include "chrome/test/chromedriver/chrome_launcher_impl.h"
+#include "base/threading/thread.h"
 #include "chrome/test/chromedriver/command.h"
 #include "chrome/test/chromedriver/command_executor.h"
 #include "chrome/test/chromedriver/session_map.h"
@@ -24,12 +24,16 @@ class DictionaryValue;
 class Value;
 }
 
+class ChromeLauncherImpl;
+class URLRequestContextGetter;
+
 class CommandExecutorImpl : public CommandExecutor {
  public:
   CommandExecutorImpl();
   virtual ~CommandExecutorImpl();
 
   // Overridden from CommandExecutor:
+  virtual void Init() OVERRIDE;
   virtual void ExecuteCommand(const std::string& name,
                               const base::DictionaryValue& params,
                               const std::string& session_id,
@@ -43,8 +47,10 @@ class CommandExecutorImpl : public CommandExecutor {
       CommandExecutorImplTest, CommandThatDoesntSetValueOrSessionId);
   FRIEND_TEST_ALL_PREFIXES(CommandExecutorImplTest, CommandThatReturnsError);
 
+  base::Thread io_thread_;
+  scoped_refptr<URLRequestContextGetter> context_getter_;
   SessionMap session_map_;
-  ChromeLauncherImpl launcher_;
+  scoped_ptr<ChromeLauncherImpl> launcher_;
   SynchronizedMap<std::string, Command> command_map_;
 
   DISALLOW_COPY_AND_ASSIGN(CommandExecutorImpl);
diff --git a/chrome/test/chromedriver/commands.cc b/chrome/test/chromedriver/commands.cc
index 8602aa3..ebf5513 100644
--- a/chrome/test/chromedriver/commands.cc
+++ b/chrome/test/chromedriver/commands.cc
@@ -78,3 +78,13 @@ Status ExecuteQuit(
   CHECK(session_map->Remove(session->id));
   return session->chrome->Quit();
 }
+
+Status ExecuteGet(
+    Session* session,
+    const base::DictionaryValue& params,
+    scoped_ptr<base::Value>* value) {
+  std::string url;
+  if (!params.GetString("url", &url))
+    return Status(kUnknownError, "'url' must be a string");
+  return session->chrome->Load(url);
+}
diff --git a/chrome/test/chromedriver/commands.h b/chrome/test/chromedriver/commands.h
index ac72f1b..3e1a68b 100644
--- a/chrome/test/chromedriver/commands.h
+++ b/chrome/test/chromedriver/commands.h
@@ -46,4 +46,10 @@ Status ExecuteQuit(
     const base::DictionaryValue& params,
     scoped_ptr<base::Value>* value);
 
+// Loads a URL.
+Status ExecuteGet(
+    Session* session,
+    const base::DictionaryValue& params,
+    scoped_ptr<base::Value>* value);
+
 #endif  // CHROME_TEST_CHROMEDRIVER_COMMANDS_H_
diff --git a/chrome/test/chromedriver/commands_unittest.cc b/chrome/test/chromedriver/commands_unittest.cc
index d7612d9..eef7136 100644
--- a/chrome/test/chromedriver/commands_unittest.cc
+++ b/chrome/test/chromedriver/commands_unittest.cc
@@ -27,6 +27,9 @@ class StubChrome : public Chrome {
   virtual ~StubChrome() {}
 
   // Overridden from Chrome:
+  virtual Status Load(const std::string& url) OVERRIDE {
+    return Status(kOk);
+  }
   virtual Status Quit() OVERRIDE {
     return Status(kOk);
   }
@@ -152,7 +155,7 @@ TEST(CommandsTest, Quit) {
 
 namespace {
 
-class FailsToQuitChrome : public Chrome {
+class FailsToQuitChrome : public StubChrome {
  public:
   FailsToQuitChrome() {}
   virtual ~FailsToQuitChrome() {}
diff --git a/chrome/test/chromedriver/devtools_client.cc b/chrome/test/chromedriver/devtools_client.cc
new file mode 100644
index 0000000..f78a492
--- /dev/null
+++ b/chrome/test/chromedriver/devtools_client.cc
@@ -0,0 +1,44 @@
+// 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.
+
+#include "chrome/test/chromedriver/devtools_client.h"
+
+#include "base/json/json_writer.h"
+#include "base/values.h"
+#include "chrome/test/chromedriver/net/sync_websocket.h"
+#include "chrome/test/chromedriver/net/url_request_context_getter.h"
+#include "chrome/test/chromedriver/status.h"
+#include "googleurl/src/gurl.h"
+
+DevToolsClient::DevToolsClient(
+    URLRequestContextGetter* context_getter,
+    const std::string& url)
+    : context_getter_(context_getter),
+      url_(url),
+      socket_(new SyncWebSocket(context_getter)),
+      connected_(false) {}
+
+DevToolsClient::~DevToolsClient() {}
+
+Status DevToolsClient::SendCommand(
+    const std::string& method,
+    const base::DictionaryValue& params) {
+  if (!connected_) {
+    if (!socket_->Connect(GURL(url_)))
+      return Status(kUnknownError, "unable to connect to renderer");
+    connected_ = true;
+  }
+  base::DictionaryValue command;
+  command.SetInteger("id", 1);
+  command.SetString("method", method);
+  command.Set("params", params.DeepCopy());
+  std::string message;
+  base::JSONWriter::Write(&command, &message);
+  if (!socket_->Send(message))
+    return Status(kUnknownError, "unable to send message to renderer");
+  std::string response;
+  if (!socket_->ReceiveNextMessage(&response))
+    return Status(kUnknownError, "unable to receive message from renderer");
+  return Status(kOk);
+}
diff --git a/chrome/test/chromedriver/devtools_client.h b/chrome/test/chromedriver/devtools_client.h
new file mode 100644
index 0000000..218632f
--- /dev/null
+++ b/chrome/test/chromedriver/devtools_client.h
@@ -0,0 +1,40 @@
+// 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.
+
+#ifndef CHROME_TEST_CHROMEDRIVER_DEVTOOLS_CLIENT_H_
+#define CHROME_TEST_CHROMEDRIVER_DEVTOOLS_CLIENT_H_
+
+#include <string>
+
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+
+namespace base {
+class DictionaryValue;
+}
+
+class Status;
+class SyncWebSocket;
+class URLRequestContextGetter;
+
+// A DevTools client of a single DevTools debugger.
+class DevToolsClient {
+ public:
+  DevToolsClient(URLRequestContextGetter* context_getter,
+                 const std::string& url);
+  ~DevToolsClient();
+
+  Status SendCommand(const std::string& method,
+                     const base::DictionaryValue& params);
+
+ private:
+  scoped_refptr<URLRequestContextGetter> context_getter_;
+  std::string url_;
+  scoped_ptr<SyncWebSocket> socket_;
+  bool connected_;
+
+  DISALLOW_COPY_AND_ASSIGN(DevToolsClient);
+};
+
+#endif  // CHROME_TEST_CHROMEDRIVER_DEVTOOLS_CLIENT_H_
diff --git a/chrome/test/chromedriver/net/net_util.cc b/chrome/test/chromedriver/net/net_util.cc
new file mode 100644
index 0000000..c6aebc3
--- /dev/null
+++ b/chrome/test/chromedriver/net/net_util.cc
@@ -0,0 +1,50 @@
+// 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.
+
+#include "base/memory/scoped_ptr.h"
+#include "base/message_loop.h"
+#include "chrome/test/chromedriver/net/url_request_context_getter.h"
+#include "googleurl/src/gurl.h"
+#include "net/url_request/url_fetcher.h"
+#include "net/url_request/url_fetcher_delegate.h"
+
+namespace {
+
+class SyncUrlFetcher : public net::URLFetcherDelegate {
+ public:
+  SyncUrlFetcher() {}
+  virtual ~SyncUrlFetcher() {}
+
+  bool Fetch(const GURL& url,
+             URLRequestContextGetter* getter,
+             std::string* response) {
+    MessageLoop loop;
+    scoped_ptr<net::URLFetcher> fetcher_(
+        net::URLFetcher::Create(url, net::URLFetcher::GET, this));
+    fetcher_->SetRequestContext(getter);
+    response_ = response;
+    fetcher_->Start();
+    loop.Run();
+    return success_;
+  }
+
+  virtual void OnURLFetchComplete(const net::URLFetcher* source) {
+    success_ = (source->GetResponseCode() == 200);
+    if (success_)
+      success_ = source->GetResponseAsString(response_);
+    MessageLoop::current()->Quit();
+  }
+
+ private:
+  bool success_;
+  std::string* response_;
+};
+
+}  // namespace
+
+bool FetchUrl(const GURL& url,
+              URLRequestContextGetter* getter,
+              std::string* response) {
+  return SyncUrlFetcher().Fetch(url, getter, response);
+}
diff --git a/chrome/test/chromedriver/net/net_util.h b/chrome/test/chromedriver/net/net_util.h
new file mode 100644
index 0000000..78ab424
--- /dev/null
+++ b/chrome/test/chromedriver/net/net_util.h
@@ -0,0 +1,19 @@
+// 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.
+
+#ifndef CHROME_TEST_CHROMEDRIVER_NET_NET_UTIL_H_
+#define CHROME_TEST_CHROMEDRIVER_NET_NET_UTIL_H_
+
+#include <string>
+
+class GURL;
+class URLRequestContextGetter;
+
+// Synchronously fetches data from a GET HTTP request to the given URL.
+// Returns true if response is 200 OK and sets response body to |response|.
+bool FetchUrl(const GURL& url,
+              URLRequestContextGetter* getter,
+              std::string* response);
+
+#endif  // CHROME_TEST_CHROMEDRIVER_NET_NET_UTIL_H_
diff --git a/chrome/test/chromedriver/net/net_util_unittest.cc b/chrome/test/chromedriver/net/net_util_unittest.cc
new file mode 100644
index 0000000..7eee142
--- /dev/null
+++ b/chrome/test/chromedriver/net/net_util_unittest.cc
@@ -0,0 +1,141 @@
+// 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.
+
+#include <string>
+
+#include "base/bind.h"
+#include "base/compiler_specific.h"
+#include "base/location.h"
+#include "base/memory/ref_counted.h"
+#include "base/message_loop.h"
+#include "base/message_loop_proxy.h"
+#include "base/single_thread_task_runner.h"
+#include "base/stringprintf.h"
+#include "base/synchronization/waitable_event.h"
+#include "base/threading/thread.h"
+#include "chrome/test/chromedriver/net/net_util.h"
+#include "chrome/test/chromedriver/net/url_request_context_getter.h"
+#include "googleurl/src/gurl.h"
+#include "net/base/ip_endpoint.h"
+#include "net/base/net_errors.h"
+#include "net/base/tcp_listen_socket.h"
+#include "net/server/http_server.h"
+#include "net/server/http_server_request_info.h"
+#include "net/url_request/url_request_context_getter.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace {
+
+class FetchUrlTest : public testing::Test,
+                     public net::HttpServer::Delegate {
+ public:
+  FetchUrlTest()
+      : io_thread_("io"),
+        response_(kSendHello) {
+    base::Thread::Options options(MessageLoop::TYPE_IO, 0);
+    CHECK(io_thread_.StartWithOptions(options));
+    context_getter_ = new URLRequestContextGetter(
+        io_thread_.message_loop_proxy());
+    base::WaitableEvent event(false, false);
+    io_thread_.message_loop_proxy()->PostTask(
+        FROM_HERE,
+        base::Bind(&FetchUrlTest::InitOnIO,
+                   base::Unretained(this), &event));
+    event.Wait();
+  }
+
+  virtual ~FetchUrlTest() {
+    base::WaitableEvent event(false, false);
+    io_thread_.message_loop_proxy()->PostTask(
+        FROM_HERE,
+        base::Bind(&FetchUrlTest::DestroyServerOnIO,
+                   base::Unretained(this), &event));
+    event.Wait();
+  }
+
+  void InitOnIO(base::WaitableEvent* event) {
+    net::TCPListenSocketFactory factory("127.0.0.1", 0);
+    server_ = new net::HttpServer(factory, this);
+    net::IPEndPoint address;
+    CHECK_EQ(net::OK, server_->GetLocalAddress(&address));
+    server_url_ = GURL(
+        base::StringPrintf("http://127.0.0.1:%d", address.port()));
+    event->Signal();
+  }
+
+  void DestroyServerOnIO(base::WaitableEvent* event) {
+    server_ = NULL;
+    event->Signal();
+  }
+
+  // Overridden from net::HttpServer::Delegate:
+  virtual void OnHttpRequest(int connection_id,
+                             const net::HttpServerRequestInfo& info) OVERRIDE {
+    switch (response_) {
+      case kSendHello:
+        server_->Send200(connection_id, "hello", "text/plain");
+        break;
+      case kSend404:
+        server_->Send404(connection_id);
+        break;
+      case kClose:
+        // net::HttpServer doesn't allow us to close connection during callback.
+        MessageLoop::current()->PostTask(
+            FROM_HERE,
+            base::Bind(&net::HttpServer::Close, server_, connection_id));
+        break;
+      default:
+        break;
+    }
+  }
+
+  virtual void OnWebSocketRequest(
+      int connection_id,
+      const net::HttpServerRequestInfo& info) OVERRIDE {}
+  virtual void OnWebSocketMessage(int connection_id,
+                                  const std::string& data) OVERRIDE {}
+  virtual void OnClose(int connection_id) OVERRIDE {}
+
+ protected:
+  enum ServerResponse {
+    kSendHello = 0,
+    kSend404,
+    kClose,
+  };
+
+  base::Thread io_thread_;
+  ServerResponse response_;
+  scoped_refptr<net::HttpServer> server_;
+  scoped_refptr<URLRequestContextGetter> context_getter_;
+  GURL server_url_;
+};
+
+}  // namespace
+
+TEST_F(FetchUrlTest, Http200) {
+  std::string response("stuff");
+  ASSERT_TRUE(FetchUrl(server_url_, context_getter_, &response));
+  ASSERT_STREQ("hello", response.c_str());
+}
+
+TEST_F(FetchUrlTest, HttpNon200) {
+  response_ = kSend404;
+  std::string response("stuff");
+  ASSERT_FALSE(FetchUrl(server_url_, context_getter_, &response));
+  ASSERT_STREQ("stuff", response.c_str());
+}
+
+TEST_F(FetchUrlTest, ConnectionClose) {
+  response_ = kClose;
+  std::string response("stuff");
+  ASSERT_FALSE(FetchUrl(server_url_, context_getter_, &response));
+  ASSERT_STREQ("stuff", response.c_str());
+}
+
+TEST_F(FetchUrlTest, NoServer) {
+  std::string response("stuff");
+  GURL bogus_url("http://localhost:33333");
+  ASSERT_FALSE(FetchUrl(bogus_url, context_getter_, &response));
+  ASSERT_STREQ("stuff", response.c_str());
+}
diff --git a/chrome/test/chromedriver/status.cc b/chrome/test/chromedriver/status.cc
index bd50279..89dc7e9 100644
--- a/chrome/test/chromedriver/status.cc
+++ b/chrome/test/chromedriver/status.cc
@@ -19,6 +19,8 @@ const char* DefaultMessageForStatusCode(StatusCode code) {
       return "session not created exception";
     case kNoSuchSession:
       return "no such session";
+    case kChromeNotReachable:
+      return "chrome not reachable";
     default:
       return "<unknown>";
   }
@@ -34,6 +36,21 @@ Status::Status(StatusCode code, const std::string& details)
       msg_(DefaultMessageForStatusCode(code) + std::string(": ") + details) {
 }
 
+Status::Status(StatusCode code, const Status& cause)
+    : code_(code),
+      msg_(DefaultMessageForStatusCode(code) + std::string("\nfrom ") +
+           cause.message()) {}
+
+Status::Status(StatusCode code,
+               const std::string& details,
+               const Status& cause)
+    : code_(code),
+      msg_(DefaultMessageForStatusCode(code) + std::string(": ") + details +
+           "\nfrom " + cause.message()) {
+}
+
+Status::~Status() {}
+
 bool Status::IsOk() const {
   return code_ == kOk;
 }
diff --git a/chrome/test/chromedriver/status.h b/chrome/test/chromedriver/status.h
index a52d6e4..7ecb808 100644
--- a/chrome/test/chromedriver/status.h
+++ b/chrome/test/chromedriver/status.h
@@ -13,7 +13,9 @@ enum StatusCode {
   kUnknownCommand = 9,
   kUnknownError = 13,
   kSessionNotCreatedException = 33,
-  kNoSuchSession = 100
+  // Chrome-specific status codes.
+  kNoSuchSession = 100,
+  kChromeNotReachable,
 };
 
 // Represents a WebDriver status, which may be an error or ok.
@@ -21,6 +23,9 @@ class Status {
  public:
   explicit Status(StatusCode code);
   Status(StatusCode code, const std::string& details);
+  Status(StatusCode code, const Status& cause);
+  Status(StatusCode code, const std::string& details, const Status& cause);
+  ~Status();
 
   bool IsOk() const;
   bool IsError() const;
diff --git a/chrome/test/chromedriver/status_unittest.cc b/chrome/test/chromedriver/status_unittest.cc
index a585afb..9946c07 100644
--- a/chrome/test/chromedriver/status_unittest.cc
+++ b/chrome/test/chromedriver/status_unittest.cc
@@ -14,17 +14,33 @@ TEST(StatusTest, Ok) {
 }
 
 TEST(StatusTest, Error) {
-  Status ok(kUnknownCommand);
-  ASSERT_FALSE(ok.IsOk());
-  ASSERT_TRUE(ok.IsError());
-  ASSERT_EQ(kUnknownCommand, ok.code());
-  ASSERT_STREQ("unknown command", ok.message().c_str());
+  Status error(kUnknownCommand);
+  ASSERT_FALSE(error.IsOk());
+  ASSERT_TRUE(error.IsError());
+  ASSERT_EQ(kUnknownCommand, error.code());
+  ASSERT_STREQ("unknown command", error.message().c_str());
 }
 
 TEST(StatusTest, ErrorWithDetails) {
-  Status ok(kUnknownError, "something happened");
-  ASSERT_FALSE(ok.IsOk());
-  ASSERT_TRUE(ok.IsError());
-  ASSERT_EQ(kUnknownError, ok.code());
-  ASSERT_STREQ("unknown error: something happened", ok.message().c_str());
+  Status error(kUnknownError, "something happened");
+  ASSERT_FALSE(error.IsOk());
+  ASSERT_TRUE(error.IsError());
+  ASSERT_EQ(kUnknownError, error.code());
+  ASSERT_STREQ("unknown error: something happened", error.message().c_str());
+}
+
+TEST(StatusTest, ErrorWithCause) {
+  Status error(
+      kUnknownCommand, "quit",
+      Status(
+          kUnknownError, "something happened",
+          Status(kSessionNotCreatedException)));
+  ASSERT_FALSE(error.IsOk());
+  ASSERT_TRUE(error.IsError());
+  ASSERT_EQ(kUnknownCommand, error.code());
+  ASSERT_STREQ(
+      "unknown command: quit\n"
+      "from unknown error: something happened\n"
+      "from session not created exception",
+      error.message().c_str());
 }
diff --git a/chrome/test/chromedriver/test.py b/chrome/test/chromedriver/test.py
index 6f17e2a..de37fc5 100644
--- a/chrome/test/chromedriver/test.py
+++ b/chrome/test/chromedriver/test.py
@@ -19,6 +19,12 @@ class ChromeDriverTest(unittest.TestCase):
     driver = chromedriver.ChromeDriver(_CHROMEDRIVER_LIB, _CHROME_BINARY)
     driver.Quit()
 
+  def testLoadUrl(self):
+    driver = chromedriver.ChromeDriver(_CHROMEDRIVER_LIB)
+    driver.Load('http://www.google.com')
+    driver.Quit()
+
+
 if __name__ == '__main__':
   if len(sys.argv) != 2 and len(sys.argv) != 3:
     print ('Usage: %s <path_to_chromedriver_so> [path_to_chrome_binary]' %