[chromedriver] Allow commands to be async.

chrome/test/chromedriver/server/http_handler.cc

Index: chrome/test/chromedriver/server/http_handler.cc
diff --git a/chrome/test/chromedriver/server/http_handler.cc b/chrome/test/chromedriver/server/http_handler.cc
index fb408b6c4f749d4b4719c5a28115dfb56bd6cbce..4699b93b56ace6cb776ec37f7847a118f755723a 100644
--- a/chrome/test/chromedriver/server/http_handler.cc
+++ b/chrome/test/chromedriver/server/http_handler.cc
@@ -23,15 +23,11 @@
 #include "chrome/test/chromedriver/chrome/log.h"
 #include "chrome/test/chromedriver/chrome/status.h"
 #include "chrome/test/chromedriver/chrome/version.h"
-#include "chrome/test/chromedriver/commands.h"
-#include "chrome/test/chromedriver/element_commands.h"
 #include "chrome/test/chromedriver/net/url_request_context_getter.h"
 #include "chrome/test/chromedriver/server/http_response.h"
 #include "chrome/test/chromedriver/session.h"
-#include "chrome/test/chromedriver/session_commands.h"
-#include "chrome/test/chromedriver/session_map.h"
+#include "chrome/test/chromedriver/session_thread_map.h"
 #include "chrome/test/chromedriver/util.h"
-#include "chrome/test/chromedriver/window_commands.h"
 #include "net/server/http_server_request_info.h"
 
 #if defined(OS_MACOSX)
@@ -44,12 +40,11 @@ const char kLocalStorage[] = "localStorage";
 const char kSessionStorage[] = "sessionStorage";
 const char kShutdownPath[] = "shutdown";
 
-Status UnimplementedCommand(
+void UnimplementedCommand(
     const base::DictionaryValue& params,
     const std::string& session_id,
-    scoped_ptr<base::Value>* value,
-    std::string* out_session_id) {
-  return Status(kUnknownCommand);
+    const CommandCallback& callback) {
+  callback.Run(Status(kUnknownCommand), scoped_ptr<base::Value>(), session_id);
 }
 
 }  // namespace
@@ -63,294 +58,411 @@ CommandMapping::~CommandMapping() {}
 
 HttpHandler::HttpHandler(Log* log, const std::string& url_base)
     : log_(log),
-      io_thread_("ChromeDriver IO"),
-      url_base_(url_base) {
+      url_base_(url_base),
+      received_shutdown_(false),
+      command_map_(new CommandMap()),
+      weak_ptr_factory_(this) {}
+
+HttpHandler::HttpHandler(
+    const scoped_refptr<base::SingleThreadTaskRunner> io_task_runner,
+    Log* log,
+    const std::string& url_base)
+    : log_(log),
+      url_base_(url_base),
+      received_shutdown_(false),
+      weak_ptr_factory_(this) {
 #if defined(OS_MACOSX)
   base::mac::ScopedNSAutoreleasePool autorelease_pool;
 #endif
-  base::Thread::Options options(base::MessageLoop::TYPE_IO, 0);
-  CHECK(io_thread_.StartWithOptions(options));
-  context_getter_ = new URLRequestContextGetter(
-      io_thread_.message_loop_proxy());
+  context_getter_ = new URLRequestContextGetter(io_task_runner);
   socket_factory_ = CreateSyncWebSocketFactory(context_getter_.get());
-  adb_.reset(new AdbImpl(io_thread_.message_loop_proxy(), log_));
+  adb_.reset(new AdbImpl(io_task_runner, log_));
   device_manager_.reset(new DeviceManager(adb_.get()));
 
   CommandMapping commands[] = {
-      CommandMapping(kPost, internal::kNewSessionPathPattern,
+      CommandMapping(kPost,
+                     internal::kNewSessionPathPattern,
                      base::Bind(&ExecuteNewSession,
-                                NewSessionParams(log_, &session_map_,
-                                    context_getter_, socket_factory_,
-                                    device_manager_.get()))),
-      CommandMapping(kGet, "session/:sessionId",
-                     WrapToCommand(
-                         base::Bind(&ExecuteGetSessionCapabilities,
-                             &session_map_))),
-      CommandMapping(kDelete, "session/:sessionId",
-                     base::Bind(&ExecuteQuit, false, &session_map_)),
-      CommandMapping(kGet, "session/:sessionId/window_handle",
+                                NewSessionParams(log_,
+                                                 &session_thread_map_,
+                                                 context_getter_,
+                                                 socket_factory_,
+                                                 device_manager_.get()))),
+      CommandMapping(kGet,
+                     "session/:sessionId",
+                     WrapToCommand(base::Bind(&ExecuteGetSessionCapabilities))),
+      CommandMapping(kDelete,
+                     "session/:sessionId",
+                     base::Bind(&ExecuteSessionCommand,
+                                &session_thread_map_,
+                                base::Bind(&ExecuteQuit, false),
+                                true)),
+      CommandMapping(kGet,
+                     "session/:sessionId/window_handle",
                      WrapToCommand(base::Bind(&ExecuteGetCurrentWindowHandle))),
-      CommandMapping(kGet, "session/:sessionId/window_handles",
+      CommandMapping(kGet,
+                     "session/:sessionId/window_handles",
                      WrapToCommand(base::Bind(&ExecuteGetWindowHandles))),
-      CommandMapping(kPost, "session/:sessionId/url",
+      CommandMapping(kPost,
+                     "session/:sessionId/url",
                      WrapToCommand(base::Bind(&ExecuteGet))),
-      CommandMapping(kGet, "session/:sessionId/alert",
-                     WrapToCommand(
-                         base::Bind(&ExecuteAlertCommand,
-                                     base::Bind(&ExecuteGetAlert)))),
-      CommandMapping(kPost, "session/:sessionId/dismiss_alert",
-                     WrapToCommand(
-                         base::Bind(&ExecuteAlertCommand,
-                                    base::Bind(&ExecuteDismissAlert)))),
-      CommandMapping(kPost, "session/:sessionId/accept_alert",
-                     WrapToCommand(
-                         base::Bind(&ExecuteAlertCommand,
-                                    base::Bind(&ExecuteAcceptAlert)))),
-      CommandMapping(kGet, "session/:sessionId/alert_text",
-                     WrapToCommand(
-                         base::Bind(&ExecuteAlertCommand,
-                                    base::Bind(&ExecuteGetAlertText)))),
-      CommandMapping(kPost, "session/:sessionId/alert_text",
-                     WrapToCommand(
-                         base::Bind(&ExecuteAlertCommand,
-                                    base::Bind(&ExecuteSetAlertValue)))),
-      CommandMapping(kPost, "session/:sessionId/forward",
+      CommandMapping(kGet,
+                     "session/:sessionId/alert",
+                     WrapToCommand(base::Bind(&ExecuteAlertCommand,
+                                              base::Bind(&ExecuteGetAlert)))),
+      CommandMapping(
+          kPost,
+          "session/:sessionId/dismiss_alert",
+          WrapToCommand(base::Bind(&ExecuteAlertCommand,
+                                   base::Bind(&ExecuteDismissAlert)))),
+      CommandMapping(
+          kPost,
+          "session/:sessionId/accept_alert",
+          WrapToCommand(base::Bind(&ExecuteAlertCommand,
+                                   base::Bind(&ExecuteAcceptAlert)))),
+      CommandMapping(
+          kGet,
+          "session/:sessionId/alert_text",
+          WrapToCommand(base::Bind(&ExecuteAlertCommand,
+                                   base::Bind(&ExecuteGetAlertText)))),
+      CommandMapping(
+          kPost,
+          "session/:sessionId/alert_text",
+          WrapToCommand(base::Bind(&ExecuteAlertCommand,
+                                   base::Bind(&ExecuteSetAlertValue)))),
+      CommandMapping(kPost,
+                     "session/:sessionId/forward",
                      WrapToCommand(base::Bind(&ExecuteGoForward))),
-      CommandMapping(kPost, "session/:sessionId/back",
+      CommandMapping(kPost,
+                     "session/:sessionId/back",
                      WrapToCommand(base::Bind(&ExecuteGoBack))),
-      CommandMapping(kPost, "session/:sessionId/refresh",
+      CommandMapping(kPost,
+                     "session/:sessionId/refresh",
                      WrapToCommand(base::Bind(&ExecuteRefresh))),
-      CommandMapping(kPost, "session/:sessionId/execute",
+      CommandMapping(kPost,
+                     "session/:sessionId/execute",
                      WrapToCommand(base::Bind(&ExecuteExecuteScript))),
-      CommandMapping(kPost, "session/:sessionId/execute_async",
+      CommandMapping(kPost,
+                     "session/:sessionId/execute_async",
                      WrapToCommand(base::Bind(&ExecuteExecuteAsyncScript))),
-      CommandMapping(kGet, "session/:sessionId/url",
+      CommandMapping(kGet,
+                     "session/:sessionId/url",
                      WrapToCommand(base::Bind(&ExecuteGetCurrentUrl))),
-      CommandMapping(kGet, "session/:sessionId/title",
+      CommandMapping(kGet,
+                     "session/:sessionId/title",
                      WrapToCommand(base::Bind(&ExecuteGetTitle))),
-      CommandMapping(kGet, "session/:sessionId/source",
+      CommandMapping(kGet,
+                     "session/:sessionId/source",
                      WrapToCommand(base::Bind(&ExecuteGetPageSource))),
-      CommandMapping(kGet, "session/:sessionId/screenshot",
+      CommandMapping(kGet,
+                     "session/:sessionId/screenshot",
                      WrapToCommand(base::Bind(&ExecuteScreenshot))),
-      CommandMapping(kPost, "session/:sessionId/visible",
+      CommandMapping(kPost,
+                     "session/:sessionId/visible",
                      base::Bind(&UnimplementedCommand)),
-      CommandMapping(kGet, "session/:sessionId/visible",
+      CommandMapping(kGet,
+                     "session/:sessionId/visible",
                      base::Bind(&UnimplementedCommand)),
-      CommandMapping(kPost, "session/:sessionId/element",
+      CommandMapping(kPost,
+                     "session/:sessionId/element",
                      WrapToCommand(base::Bind(&ExecuteFindElement, 50))),
-      CommandMapping(kPost, "session/:sessionId/elements",
+      CommandMapping(kPost,
+                     "session/:sessionId/elements",
                      WrapToCommand(base::Bind(&ExecuteFindElements, 50))),
-      CommandMapping(kPost, "session/:sessionId/element/active",
+      CommandMapping(kPost,
+                     "session/:sessionId/element/active",
                      WrapToCommand(base::Bind(&ExecuteGetActiveElement))),
-      CommandMapping(kPost, "session/:sessionId/element/:id/element",
+      CommandMapping(kPost,
+                     "session/:sessionId/element/:id/element",
                      WrapToCommand(base::Bind(&ExecuteFindChildElement, 50))),
-      CommandMapping(kPost, "session/:sessionId/element/:id/elements",
+      CommandMapping(kPost,
+                     "session/:sessionId/element/:id/elements",
                      WrapToCommand(base::Bind(&ExecuteFindChildElements, 50))),
-      CommandMapping(kPost, "session/:sessionId/element/:id/click",
+      CommandMapping(kPost,
+                     "session/:sessionId/element/:id/click",
                      WrapToCommand(base::Bind(&ExecuteClickElement))),
-      CommandMapping(kPost, "session/:sessionId/element/:id/clear",
+      CommandMapping(kPost,
+                     "session/:sessionId/element/:id/clear",
                      WrapToCommand(base::Bind(&ExecuteClearElement))),
-      CommandMapping(kPost, "session/:sessionId/element/:id/submit",
+      CommandMapping(kPost,
+                     "session/:sessionId/element/:id/submit",
                      WrapToCommand(base::Bind(&ExecuteSubmitElement))),
-      CommandMapping(kGet, "session/:sessionId/element/:id/text",
+      CommandMapping(kGet,
+                     "session/:sessionId/element/:id/text",
                      WrapToCommand(base::Bind(&ExecuteGetElementText))),
-      CommandMapping(kPost, "session/:sessionId/element/:id/value",
+      CommandMapping(kPost,
+                     "session/:sessionId/element/:id/value",
                      WrapToCommand(base::Bind(&ExecuteSendKeysToElement))),
-      CommandMapping(kPost, "session/:sessionId/file",
+      CommandMapping(kPost,
+                     "session/:sessionId/file",
                      WrapToCommand(base::Bind(&ExecuteUploadFile))),
-      CommandMapping(kGet, "session/:sessionId/element/:id/value",
+      CommandMapping(kGet,
+                     "session/:sessionId/element/:id/value",
                      WrapToCommand(base::Bind(&ExecuteGetElementValue))),
-      CommandMapping(kGet, "session/:sessionId/element/:id/name",
+      CommandMapping(kGet,
+                     "session/:sessionId/element/:id/name",
                      WrapToCommand(base::Bind(&ExecuteGetElementTagName))),
-      CommandMapping(kGet, "session/:sessionId/element/:id/selected",
+      CommandMapping(kGet,
+                     "session/:sessionId/element/:id/selected",
                      WrapToCommand(base::Bind(&ExecuteIsElementSelected))),
-      CommandMapping(kGet, "session/:sessionId/element/:id/enabled",
+      CommandMapping(kGet,
+                     "session/:sessionId/element/:id/enabled",
                      WrapToCommand(base::Bind(&ExecuteIsElementEnabled))),
-      CommandMapping(kGet, "session/:sessionId/element/:id/displayed",
+      CommandMapping(kGet,
+                     "session/:sessionId/element/:id/displayed",
                      WrapToCommand(base::Bind(&ExecuteIsElementDisplayed))),
-      CommandMapping(kPost, "session/:sessionId/element/:id/hover",
+      CommandMapping(kPost,
+                     "session/:sessionId/element/:id/hover",
                      WrapToCommand(base::Bind(&ExecuteHoverOverElement))),
-      CommandMapping(kGet, "session/:sessionId/element/:id/location",
+      CommandMapping(kGet,
+                     "session/:sessionId/element/:id/location",
                      WrapToCommand(base::Bind(&ExecuteGetElementLocation))),
-      CommandMapping(kGet, "session/:sessionId/element/:id/location_in_view",
-                     WrapToCommand(
-                         base::Bind(
-                             &ExecuteGetElementLocationOnceScrolledIntoView))),
-      CommandMapping(kGet, "session/:sessionId/element/:id/size",
+      CommandMapping(kGet,
+                     "session/:sessionId/element/:id/location_in_view",
+                     WrapToCommand(base::Bind(
+                         &ExecuteGetElementLocationOnceScrolledIntoView))),
+      CommandMapping(kGet,
+                     "session/:sessionId/element/:id/size",
                      WrapToCommand(base::Bind(&ExecuteGetElementSize))),
-      CommandMapping(kGet, "session/:sessionId/element/:id/attribute/:name",
+      CommandMapping(kGet,
+                     "session/:sessionId/element/:id/attribute/:name",
                      WrapToCommand(base::Bind(&ExecuteGetElementAttribute))),
-      CommandMapping(kGet, "session/:sessionId/element/:id/equals/:other",
+      CommandMapping(kGet,
+                     "session/:sessionId/element/:id/equals/:other",
                      WrapToCommand(base::Bind(&ExecuteElementEquals))),
-      CommandMapping(kGet, "session/:sessionId/cookie",
+      CommandMapping(kGet,
+                     "session/:sessionId/cookie",
                      WrapToCommand(base::Bind(&ExecuteGetCookies))),
-      CommandMapping(kPost, "session/:sessionId/cookie",
+      CommandMapping(kPost,
+                     "session/:sessionId/cookie",
                      WrapToCommand(base::Bind(&ExecuteAddCookie))),
-      CommandMapping(kDelete, "session/:sessionId/cookie",
+      CommandMapping(kDelete,
+                     "session/:sessionId/cookie",
                      WrapToCommand(base::Bind(&ExecuteDeleteAllCookies))),
-      CommandMapping(kDelete, "session/:sessionId/cookie/:name",
+      CommandMapping(kDelete,
+                     "session/:sessionId/cookie/:name",
                      WrapToCommand(base::Bind(&ExecuteDeleteCookie))),
-      CommandMapping(kPost, "session/:sessionId/frame",
+      CommandMapping(kPost,
+                     "session/:sessionId/frame",
                      WrapToCommand(base::Bind(&ExecuteSwitchToFrame))),
-      CommandMapping(kPost, "session/:sessionId/window",
+      CommandMapping(kPost,
+                     "session/:sessionId/window",
                      WrapToCommand(base::Bind(&ExecuteSwitchToWindow))),
-      CommandMapping(kGet, "session/:sessionId/window/:windowHandle/size",
+      CommandMapping(kGet,
+                     "session/:sessionId/window/:windowHandle/size",
                      WrapToCommand(base::Bind(&ExecuteGetWindowSize))),
-      CommandMapping(kGet, "session/:sessionId/window/:windowHandle/position",
+      CommandMapping(kGet,
+                     "session/:sessionId/window/:windowHandle/position",
                      WrapToCommand(base::Bind(&ExecuteGetWindowPosition))),
-      CommandMapping(kPost, "session/:sessionId/window/:windowHandle/size",
+      CommandMapping(kPost,
+                     "session/:sessionId/window/:windowHandle/size",
                      WrapToCommand(base::Bind(&ExecuteSetWindowSize))),
-      CommandMapping(kPost, "session/:sessionId/window/:windowHandle/position",
+      CommandMapping(kPost,
+                     "session/:sessionId/window/:windowHandle/position",
                      WrapToCommand(base::Bind(&ExecuteSetWindowPosition))),
-      CommandMapping(kPost, "session/:sessionId/window/:windowHandle/maximize",
+      CommandMapping(kPost,
+                     "session/:sessionId/window/:windowHandle/maximize",
                      WrapToCommand(base::Bind(&ExecuteMaximizeWindow))),
-      CommandMapping(kDelete, "session/:sessionId/window",
-                     WrapToCommand(base::Bind(&ExecuteClose, &session_map_))),
-      CommandMapping(kPost, "session/:sessionId/element/:id/drag",
+      CommandMapping(kDelete,
+                     "session/:sessionId/window",
+                     WrapToCommand(base::Bind(&ExecuteClose))),
+      CommandMapping(kPost,
+                     "session/:sessionId/element/:id/drag",
                      base::Bind(&UnimplementedCommand)),
-      CommandMapping(kGet, "session/:sessionId/element/:id/css/:propertyName",
-                     WrapToCommand(
-                         base::Bind(&ExecuteGetElementValueOfCSSProperty))),
-      CommandMapping(kPost, "session/:sessionId/timeouts/implicit_wait",
+      CommandMapping(
+          kGet,
+          "session/:sessionId/element/:id/css/:propertyName",
+          WrapToCommand(base::Bind(&ExecuteGetElementValueOfCSSProperty))),
+      CommandMapping(kPost,
+                     "session/:sessionId/timeouts/implicit_wait",
                      WrapToCommand(base::Bind(&ExecuteImplicitlyWait))),
-      CommandMapping(kPost, "session/:sessionId/timeouts/async_script",
+      CommandMapping(kPost,
+                     "session/:sessionId/timeouts/async_script",
                      WrapToCommand(base::Bind(&ExecuteSetScriptTimeout))),
-      CommandMapping(kPost, "session/:sessionId/timeouts",
+      CommandMapping(kPost,
+                     "session/:sessionId/timeouts",
                      WrapToCommand(base::Bind(&ExecuteSetTimeout))),
-      CommandMapping(kPost, "session/:sessionId/execute_sql",
+      CommandMapping(kPost,
+                     "session/:sessionId/execute_sql",
                      base::Bind(&UnimplementedCommand)),
-      CommandMapping(kGet, "session/:sessionId/location",
+      CommandMapping(kGet,
+                     "session/:sessionId/location",
                      WrapToCommand(base::Bind(&ExecuteGetLocation))),
-      CommandMapping(kPost, "session/:sessionId/location",
+      CommandMapping(kPost,
+                     "session/:sessionId/location",
                      WrapToCommand(base::Bind(&ExecuteSetLocation))),
-      CommandMapping(kGet, "session/:sessionId/application_cache/status",
+      CommandMapping(kGet,
+                     "session/:sessionId/application_cache/status",
                      base::Bind(&ExecuteGetStatus)),
-      CommandMapping(kGet, "session/:sessionId/browser_connection",
+      CommandMapping(kGet,
+                     "session/:sessionId/browser_connection",
                      base::Bind(&UnimplementedCommand)),
-      CommandMapping(kPost, "session/:sessionId/browser_connection",
+      CommandMapping(kPost,
+                     "session/:sessionId/browser_connection",
                      base::Bind(&UnimplementedCommand)),
-      CommandMapping(kGet, "session/:sessionId/local_storage/key/:key",
-                     WrapToCommand(
-                         base::Bind(&ExecuteGetStorageItem, kLocalStorage))),
-      CommandMapping(kDelete, "session/:sessionId/local_storage/key/:key",
-                     WrapToCommand(
-                         base::Bind(&ExecuteRemoveStorageItem, kLocalStorage))),
-      CommandMapping(kGet, "session/:sessionId/local_storage",
-                     WrapToCommand(
-                         base::Bind(&ExecuteGetStorageKeys, kLocalStorage))),
-      CommandMapping(kPost, "session/:sessionId/local_storage",
-                     WrapToCommand(
-                         base::Bind(&ExecuteSetStorageItem, kLocalStorage))),
-      CommandMapping(kDelete, "session/:sessionId/local_storage",
-                     WrapToCommand(
-                         base::Bind(&ExecuteClearStorage, kLocalStorage))),
-      CommandMapping(kGet, "session/:sessionId/local_storage/size",
-                     WrapToCommand(
-                         base::Bind(&ExecuteGetStorageSize, kLocalStorage))),
-      CommandMapping(kGet, "session/:sessionId/session_storage/key/:key",
-                     WrapToCommand(
-                         base::Bind(&ExecuteGetStorageItem, kSessionStorage))),
-      CommandMapping(kDelete, "session/:sessionId/session_storage/key/:key",
-                     WrapToCommand(
-                         base::Bind(
-                             &ExecuteRemoveStorageItem, kSessionStorage))),
-      CommandMapping(kGet, "session/:sessionId/session_storage",
-                     WrapToCommand(
-                         base::Bind(&ExecuteGetStorageKeys, kSessionStorage))),
-      CommandMapping(kPost, "session/:sessionId/session_storage",
-                     WrapToCommand(
-                         base::Bind(&ExecuteSetStorageItem, kSessionStorage))),
-      CommandMapping(kDelete, "session/:sessionId/session_storage",
-                     WrapToCommand(
-                         base::Bind(&ExecuteClearStorage, kSessionStorage))),
-      CommandMapping(kGet, "session/:sessionId/session_storage/size",
-                     WrapToCommand(
-                         base::Bind(&ExecuteGetStorageSize, kSessionStorage))),
-      CommandMapping(kGet, "session/:sessionId/orientation",
+      CommandMapping(
+          kGet,
+          "session/:sessionId/local_storage/key/:key",
+          WrapToCommand(base::Bind(&ExecuteGetStorageItem, kLocalStorage))),
+      CommandMapping(
+          kDelete,
+          "session/:sessionId/local_storage/key/:key",
+          WrapToCommand(base::Bind(&ExecuteRemoveStorageItem, kLocalStorage))),
+      CommandMapping(
+          kGet,
+          "session/:sessionId/local_storage",
+          WrapToCommand(base::Bind(&ExecuteGetStorageKeys, kLocalStorage))),
+      CommandMapping(
+          kPost,
+          "session/:sessionId/local_storage",
+          WrapToCommand(base::Bind(&ExecuteSetStorageItem, kLocalStorage))),
+      CommandMapping(
+          kDelete,
+          "session/:sessionId/local_storage",
+          WrapToCommand(base::Bind(&ExecuteClearStorage, kLocalStorage))),
+      CommandMapping(
+          kGet,
+          "session/:sessionId/local_storage/size",
+          WrapToCommand(base::Bind(&ExecuteGetStorageSize, kLocalStorage))),
+      CommandMapping(
+          kGet,
+          "session/:sessionId/session_storage/key/:key",
+          WrapToCommand(base::Bind(&ExecuteGetStorageItem, kSessionStorage))),
+      CommandMapping(kDelete,
+                     "session/:sessionId/session_storage/key/:key",
+                     WrapToCommand(base::Bind(&ExecuteRemoveStorageItem,
+                                              kSessionStorage))),
+      CommandMapping(
+          kGet,
+          "session/:sessionId/session_storage",
+          WrapToCommand(base::Bind(&ExecuteGetStorageKeys, kSessionStorage))),
+      CommandMapping(
+          kPost,
+          "session/:sessionId/session_storage",
+          WrapToCommand(base::Bind(&ExecuteSetStorageItem, kSessionStorage))),
+      CommandMapping(
+          kDelete,
+          "session/:sessionId/session_storage",
+          WrapToCommand(base::Bind(&ExecuteClearStorage, kSessionStorage))),
+      CommandMapping(
+          kGet,
+          "session/:sessionId/session_storage/size",
+          WrapToCommand(base::Bind(&ExecuteGetStorageSize, kSessionStorage))),
+      CommandMapping(kGet,
+                     "session/:sessionId/orientation",
                      base::Bind(&UnimplementedCommand)),
-      CommandMapping(kPost, "session/:sessionId/orientation",
+      CommandMapping(kPost,
+                     "session/:sessionId/orientation",
                      base::Bind(&UnimplementedCommand)),
-      CommandMapping(kPost, "session/:sessionId/click",
+      CommandMapping(kPost,
+                     "session/:sessionId/click",
                      WrapToCommand(base::Bind(&ExecuteMouseClick))),
-      CommandMapping(kPost, "session/:sessionId/doubleclick",
+      CommandMapping(kPost,
+                     "session/:sessionId/doubleclick",
                      WrapToCommand(base::Bind(&ExecuteMouseDoubleClick))),
-      CommandMapping(kPost, "session/:sessionId/buttondown",
+      CommandMapping(kPost,
+                     "session/:sessionId/buttondown",
                      WrapToCommand(base::Bind(&ExecuteMouseButtonDown))),
-      CommandMapping(kPost, "session/:sessionId/buttonup",
+      CommandMapping(kPost,
+                     "session/:sessionId/buttonup",
                      WrapToCommand(base::Bind(&ExecuteMouseButtonUp))),
-      CommandMapping(kPost, "session/:sessionId/moveto",
+      CommandMapping(kPost,
+                     "session/:sessionId/moveto",
                      WrapToCommand(base::Bind(&ExecuteMouseMoveTo))),
-      CommandMapping(kPost, "session/:sessionId/keys",
-                     WrapToCommand(
-                         base::Bind(&ExecuteSendKeysToActiveElement))),
-      CommandMapping(kGet, "session/:sessionId/ime/available_engines",
+      CommandMapping(
+          kPost,
+          "session/:sessionId/keys",
+          WrapToCommand(base::Bind(&ExecuteSendKeysToActiveElement))),
+      CommandMapping(kGet,
+                     "session/:sessionId/ime/available_engines",
                      base::Bind(&UnimplementedCommand)),
-      CommandMapping(kGet, "session/:sessionId/ime/active_engine",
+      CommandMapping(kGet,
+                     "session/:sessionId/ime/active_engine",
                      base::Bind(&UnimplementedCommand)),
-      CommandMapping(kGet, "session/:sessionId/ime/activated",
+      CommandMapping(kGet,
+                     "session/:sessionId/ime/activated",
                      base::Bind(&UnimplementedCommand)),
-      CommandMapping(kPost, "session/:sessionId/ime/deactivate",
+      CommandMapping(kPost,
+                     "session/:sessionId/ime/deactivate",
                      base::Bind(&UnimplementedCommand)),
-      CommandMapping(kPost, "session/:sessionId/ime/activate",
+      CommandMapping(kPost,
+                     "session/:sessionId/ime/activate",
                      base::Bind(&UnimplementedCommand)),
-      CommandMapping(kPost, "session/:sessionId/touch/click",
+      CommandMapping(kPost,
+                     "session/:sessionId/touch/click",
                      WrapToCommand(base::Bind(&ExecuteTouchSingleTap))),
-      CommandMapping(kPost, "session/:sessionId/touch/down",
+      CommandMapping(kPost,
+                     "session/:sessionId/touch/down",
                      base::Bind(&UnimplementedCommand)),
-      CommandMapping(kPost, "session/:sessionId/touch/up",
+      CommandMapping(kPost,
+                     "session/:sessionId/touch/up",
                      base::Bind(&UnimplementedCommand)),
-      CommandMapping(kPost, "session/:sessionId/touch/move",
+      CommandMapping(kPost,
+                     "session/:sessionId/touch/move",
                      base::Bind(&UnimplementedCommand)),
-      CommandMapping(kPost, "session/:sessionId/touch/scroll",
+      CommandMapping(kPost,
+                     "session/:sessionId/touch/scroll",
                      base::Bind(&UnimplementedCommand)),
-      CommandMapping(kPost, "session/:sessionId/touch/doubleclick",
+      CommandMapping(kPost,
+                     "session/:sessionId/touch/doubleclick",
                      base::Bind(&UnimplementedCommand)),
-      CommandMapping(kPost, "session/:sessionId/touch/longclick",
+      CommandMapping(kPost,
+                     "session/:sessionId/touch/longclick",
                      base::Bind(&UnimplementedCommand)),
-      CommandMapping(kPost, "session/:sessionId/touch/flick",
+      CommandMapping(kPost,
+                     "session/:sessionId/touch/flick",
                      base::Bind(&UnimplementedCommand)),
-      CommandMapping(kPost, "session/:sessionId/log",
+      CommandMapping(kPost,
+                     "session/:sessionId/log",
                      WrapToCommand(base::Bind(&ExecuteGetLog))),
-      CommandMapping(kGet, "session/:sessionId/log/types",
+      CommandMapping(kGet,
+                     "session/:sessionId/log/types",
                      WrapToCommand(base::Bind(&ExecuteGetAvailableLogTypes))),
       CommandMapping(kPost, "logs", base::Bind(&UnimplementedCommand)),
       CommandMapping(kGet, "status", base::Bind(&ExecuteGetStatus)),
 
       // Custom Chrome commands:
       // Allow quit all to be called with GET or POST.
-      CommandMapping(kGet, kShutdownPath,
+      CommandMapping(kGet,
+                     kShutdownPath,
                      base::Bind(&ExecuteQuitAll,
-                                base::Bind(&ExecuteQuit, true, &session_map_),
-                                &session_map_)),
-      CommandMapping(kPost, kShutdownPath,
+                                WrapToCommand(base::Bind(&ExecuteQuit, true)),
+                                &session_thread_map_)),
+      CommandMapping(kPost,
+                     kShutdownPath,
                      base::Bind(&ExecuteQuitAll,
-                                base::Bind(&ExecuteQuit, true, &session_map_),
-                                &session_map_)),
-      CommandMapping(kGet, "session/:sessionId/is_loading",
-                     WrapToCommand(base::Bind(&ExecuteIsLoading))),
-  };
-  this->command_map_.reset(
+                                WrapToCommand(base::Bind(&ExecuteQuit, true)),
+                                &session_thread_map_)),
+      CommandMapping(kGet,
+                     "session/:sessionId/is_loading",
+                     WrapToCommand(base::Bind(&ExecuteIsLoading))), };
+  command_map_.reset(
       new CommandMap(commands, commands + arraysize(commands)));
 }
 
 HttpHandler::~HttpHandler() {}
 
 void HttpHandler::Handle(const net::HttpServerRequestInfo& request,
-                         HttpResponse* response) {
-  log_->AddEntry(
-      Log::kLog,
-      base::StringPrintf("received WebDriver request: %s %s %s",
-                         request.method.c_str(),
-                         request.path.c_str(),
-                         request.data.c_str()));
-
-  HandleInternal(request, response);
-
-  log_->AddEntry(
-      Log::kLog,
-      base::StringPrintf("sending WebDriver response: %d %s",
-                         response->status(),
-                         response->body().c_str()));
+                         const HttpResponseSenderFunc& send_response_func) {
+  CHECK(thread_checker_.CalledOnValidThread());
+
+  if (received_shutdown_)
+    return;
+  if (ShouldShutdown(request))
+    received_shutdown_ = true;
+
+  std::string path = request.path;
+  if (!StartsWithASCII(path, url_base_, true)) {
+    scoped_ptr<HttpResponse> response(
+        new HttpResponse(HttpResponse::kBadRequest));
+    response->set_body("unhandled request");
+    send_response_func.Run(response.Pass());
+    return;
+  }
+
+  path.erase(0, url_base_.length());
+
+  HandleCommand(request, path, send_response_func);
 }
 
 bool HttpHandler::ShouldShutdown(const net::HttpServerRequestInfo& request) {
@@ -359,7 +471,8 @@ bool HttpHandler::ShouldShutdown(const net::HttpServerRequestInfo& request) {
 
 Command HttpHandler::WrapToCommand(
     const SessionCommand& session_command) {
-  return base::Bind(&ExecuteSessionCommand, &session_map_, session_command);
+  return base::Bind(
+      &ExecuteSessionCommand, &session_thread_map_, session_command, false);
 }
 
 Command HttpHandler::WrapToCommand(
@@ -374,34 +487,26 @@ Command HttpHandler::WrapToCommand(
       base::Bind(&ExecuteElementCommand, element_command));
 }
 
-void HttpHandler::HandleInternal(const net::HttpServerRequestInfo& request,
-                                 HttpResponse* response) {
-  std::string path = request.path;
-  if (!StartsWithASCII(path, url_base_, true)) {
-    *response = HttpResponse(HttpResponse::kBadRequest);
-    response->set_body("unhandled request");
-    return;
-  }
-
-  path.erase(0, url_base_.length());
-
-  if (!HandleWebDriverCommand(request, path, response)) {
-    *response = HttpResponse(HttpResponse::kNotFound);
-    response->set_body("unknown command: " + path);
-    return;
-  }
-}
-
-bool HttpHandler::HandleWebDriverCommand(
+void HttpHandler::HandleCommand(
     const net::HttpServerRequestInfo& request,
     const std::string& trimmed_path,
-    HttpResponse* response) {
+    const HttpResponseSenderFunc& send_response_func) {
+  log_->AddEntry(Log::kLog,
+                 base::StringPrintf("handling command: %s %s %s",
+                                    request.method.c_str(),
+                                    trimmed_path.c_str(),
+                                    request.data.c_str()));
+
   base::DictionaryValue params;
   std::string session_id;
   CommandMap::const_iterator iter = command_map_->begin();
   while (true) {
     if (iter == command_map_->end()) {
-      return false;
+      scoped_ptr<HttpResponse> response(
+          new HttpResponse(HttpResponse::kNotFound));
+      response->set_body("unknown command: " + trimmed_path);
+      send_response_func.Run(response.Pass());
+      return;
     }
     if (internal::MatchesCommand(
             request.method, trimmed_path, *iter, &session_id, &params)) {
@@ -414,40 +519,69 @@ bool HttpHandler::HandleWebDriverCommand(
     base::DictionaryValue* body_params;
     scoped_ptr<base::Value> parsed_body(base::JSONReader::Read(request.data));
     if (!parsed_body || !parsed_body->GetAsDictionary(&body_params)) {
-      *response = HttpResponse(HttpResponse::kBadRequest);
+      scoped_ptr<HttpResponse> response(
+          new HttpResponse(HttpResponse::kBadRequest));
       response->set_body("missing command parameters");
-      return true;
+      send_response_func.Run(response.Pass());
+      return;
     }
     params.MergeDictionary(body_params);
   }
 
-  scoped_ptr<base::Value> value;
-  std::string out_session_id;
-  Status status = iter->command.Run(
-      params, session_id, &value, &out_session_id);
+  iter->command.Run(params,
+                    session_id,
+                    base::Bind(&HttpHandler::PrepareResponse,
+                               weak_ptr_factory_.GetWeakPtr(),
+                               trimmed_path,
+                               send_response_func));
+}
+
+void HttpHandler::PrepareResponse(
+    const std::string& trimmed_path,
+    const HttpResponseSenderFunc& send_response_func,
+    const Status& status,
+    scoped_ptr<base::Value> value,
+    const std::string& session_id) {
+  CHECK(thread_checker_.CalledOnValidThread());
+  scoped_ptr<HttpResponse> response =
+      PrepareResponseHelper(trimmed_path, status, value.Pass(), session_id);
+  log_->AddEntry(Log::kLog,
+                 base::StringPrintf("sending response: %d %s",
+                                    response->status(),
+                                    response->body().c_str()));
+  send_response_func.Run(response.Pass());
+}
 
+scoped_ptr<HttpResponse> HttpHandler::PrepareResponseHelper(
+    const std::string& trimmed_path,
+    const Status& status,
+    scoped_ptr<base::Value> value,
+    const std::string& session_id) {
   if (status.code() == kUnknownCommand) {
-    *response = HttpResponse(HttpResponse::kNotImplemented);
+    scoped_ptr<HttpResponse> response(
+        new HttpResponse(HttpResponse::kNotImplemented));
     response->set_body("unimplemented command: " + trimmed_path);
-    return true;
+    return response.Pass();
   }
 
-  if (iter->path_pattern == internal::kNewSessionPathPattern && status.IsOk()) {
+  if (trimmed_path == internal::kNewSessionPathPattern && status.IsOk()) {
     // Creating a session involves a HTTP request to /session, which is
     // supposed to redirect to /session/:sessionId, which returns the
     // session info.
-    *response = HttpResponse(HttpResponse::kSeeOther);
-    response->AddHeader("Location", url_base_ + "session/" + out_session_id);
-    return true;
+    scoped_ptr<HttpResponse> response(
+        new HttpResponse(HttpResponse::kSeeOther));
+    response->AddHeader("Location", url_base_ + "session/" + session_id);
+    return response.Pass();
   } else if (status.IsError()) {
-    status.AddDetails(base::StringPrintf(
+    Status full_status(status);
+    full_status.AddDetails(base::StringPrintf(
         "Driver info: chromedriver=%s,platform=%s %s %s",
         kChromeDriverVersion,
         base::SysInfo::OperatingSystemName().c_str(),
         base::SysInfo::OperatingSystemVersion().c_str(),
         base::SysInfo::OperatingSystemArchitecture().c_str()));
     scoped_ptr<base::DictionaryValue> error(new base::DictionaryValue());
-    error->SetString("message", status.message());
+    error->SetString("message", full_status.message());
     value.reset(error.release());
   }
   if (!value)
@@ -456,15 +590,15 @@ bool HttpHandler::HandleWebDriverCommand(
   base::DictionaryValue body_params;
   body_params.SetInteger("status", status.code());
   body_params.Set("value", value.release());
-  body_params.SetString("sessionId", out_session_id);
+  body_params.SetString("sessionId", session_id);
   std::string body;
   base::JSONWriter::WriteWithOptions(
       &body_params, base::JSONWriter::OPTIONS_OMIT_DOUBLE_TYPE_PRESERVATION,
       &body);
-  *response = HttpResponse(HttpResponse::kOk);
+  scoped_ptr<HttpResponse> response(new HttpResponse(HttpResponse::kOk));
   response->SetMimeType("application/json; charset=utf-8");
   response->set_body(body);
-  return true;
+  return response.Pass();
 }
 
 namespace internal {