CommandLine: add a CopySwitchesFrom() for copying from another CommandLine

chrome/browser/extensions/extension_uitest.cc

 // Copyright (c) 2010 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/command_line.h"
 #include "base/json/json_reader.h"
 #include "base/json/json_writer.h"
 #include "base/values.h"
 #include "chrome/browser/automation/extension_automation_constants.h"
 #include "chrome/browser/extensions/extension_tabs_module_constants.h"
@@ skipping 39 matching lines @@
 // through code, instead of having to contort the browser into a state
 // suitable for testing.
 //
 // By default, makes Chrome forward all Chrome Extension API function calls
 // via the automation interface. To override this, call set_functions_enabled()
 // with a list of function names that should be forwarded,
 class ExtensionUITest : public ExternalTabUITest {
  public:
    explicit ExtensionUITest(const std::string& extension_path)
       : loop_(MessageLoop::current()) {
-    FilePath filename(test_data_directory_);
-    filename = filename.AppendASCII(extension_path);
-    launch_arguments_.AppendSwitchWithValue(switches::kLoadExtension,
-                                            filename.value());
+    FilePath filename = test_data_directory_.AppendASCII(extension_path);
+    launch_arguments_.AppendSwitchPath(switches::kLoadExtension, filename);
     functions_enabled_.push_back("*");
   }
 
   void set_functions_enabled(
       const std::vector<std::string>& functions_enabled) {
     functions_enabled_ = functions_enabled;
   }
 
   void SetUp() {
     ExternalTabUITest::SetUp();
@@ skipping 407 matching lines @@
   ASSERT_EQ(arraysize(events_), event_count_.size());
   for (std::map<std::string, int>::iterator i = event_count_.begin();
       i != event_count_.end(); ++i) {
     const std::pair<std::string, int>& value = *i;
     EXPECT_EQ(1, value.second);
   }
 }
 #endif  // defined(OS_WIN)
 
 }  // namespace