[chromedriver] Ensure GetLog works even if the current tab is closed.

chrome/test/chromedriver/session_commands.cc

 // Copyright (c) 2013 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/session_commands.h"
 
 #include <list>
 #include <utility>
 
 #include "base/bind.h"
@@ skipping 53 matching lines @@
 bool WindowHandleToWebViewId(const std::string& window_handle,
                              std::string* web_view_id) {
   if (!base::StartsWith(window_handle, kWindowHandlePrefix,
                         base::CompareCase::SENSITIVE)) {
     return false;
   }
   *web_view_id = window_handle.substr(sizeof(kWindowHandlePrefix) - 1);
   return true;
 }
 
+Status EvaluateScriptAndIgnoreResult(Session* session, std::string expression) {
+  WebView* web_view = nullptr;
+  Status status = session->GetTargetWindow(&web_view);
+  if (status.IsError())
+    return status;
+  std::string frame_id = session->GetCurrentFrameId();
+  std::unique_ptr<base::Value> result;
+  return web_view->EvaluateScript(frame_id, expression, &result);
+}
+
 }  // namespace
 
 InitSessionParams::InitSessionParams(
     scoped_refptr<URLRequestContextGetter> context_getter,
     const SyncWebSocketFactory& socket_factory,
     DeviceManager* device_manager,
     PortServer* port_server,
     PortManager* port_manager)
     : context_getter(context_getter),
       socket_factory(socket_factory),
@@ skipping 654 matching lines @@
 }
 
 Status ExecuteGetLog(Session* session,
                      const base::DictionaryValue& params,
                      std::unique_ptr<base::Value>* value) {
   std::string log_type;
   if (!params.GetString("type", &log_type)) {
     return Status(kUnknownError, "missing or invalid 'type'");
   }
 
-  WebView* web_view = NULL;
-  Status status = session->GetTargetWindow(&web_view);
-  if (status.IsError())
-    return status;
-
-  base::ListValue args;
-  std::unique_ptr<base::Value> result;
-  status = web_view->CallFunction(session->GetCurrentFrameId(),
-                                  "function(s) { return 1; }", args, &result);
-  if (status.IsError())
-    return status;
-
-  int response;
-  if (!result->GetAsInteger(&response) || response != 1)
-    return Status(kUnknownError, "unexpected response from browser");
+  // Evaluate a JavaScript in the renderer process for the current tab, to flush
+  // out any pending logging-related events.
+  Status status = EvaluateScriptAndIgnoreResult(session, "1");
+  if (status.IsError()) {
+    // Sometimes a WebDriver client fetches logs to diagnose an error that has
+    // occurred. It's possible that in the case of an error, the renderer is no
+    // be longer available, but we should return the logs anyway. So log (but
+    // don't fail on) any error that we get while evaluating the script.
+    LOG(WARNING) << "Unable to evaluate script: " << status.message();
+  }
 
   std::vector<WebDriverLog*> logs = session->GetAllLogs();
   for (std::vector<WebDriverLog*>::const_iterator log = logs.begin();
        log != logs.end();
        ++log) {
     if (log_type == (*log)->type()) {
       *value = (*log)->GetAndClearEntries();
       return Status(kOk);
     }
   }
@@ skipping 93 matching lines @@
                                       std::unique_ptr<base::Value>* value) {
   WebView* web_view = nullptr;
   Status status = session->GetTargetWindow(&web_view);
   if (status.IsError())
     return status;
   status = web_view->DeleteScreenOrientation();
   if (status.IsError())
     return status;
   return Status(kOk);
 }