DevTools: add custom-devtools-frontend flag for content shell layout tests

content/shell/common/layout_test/layout_test_switches.cc

 // Copyright 2016 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 "content/shell/common/layout_test/layout_test_switches.h"
 
 #include "base/command_line.h"
 #include "base/strings/string_split.h"
 
 namespace switches {
 
 // Allow access to external pages during layout tests.
 const char kAllowExternalPages[] = "allow-external-pages";
 
 // Check whether all system dependencies for running layout tests are met.
 const char kCheckLayoutTestSysDeps[] = "check-layout-test-sys-deps";
 
 // When specified to "enable-leak-detection" command-line option,
 // causes the leak detector to cause immediate crash when found leak.
 const char kCrashOnFailure[] = "crash-on-failure";
 
 // Run devtools tests in debug mode (not bundled and minified)
 const char kDebugDevTools[] = "debug-devtools";
 
+// Specify a custom path to devtools for devtools tests
+const char kCustomDevToolsFrontend[] = "custom-devtools-frontend";
+
 // Enable accelerated 2D canvas.
 const char kEnableAccelerated2DCanvas[] = "enable-accelerated-2d-canvas";
 
 // Enable font antialiasing for pixel tests.
 const char kEnableFontAntialiasing[] = "enable-font-antialiasing";
 
 // Always use the complex text path for layout tests.
 const char kAlwaysUseComplexText[] = "always-use-complex-text";
 
 // Enables the leak detection of loading webpages. This allows us to check
 // whether or not reloading a webpage releases web-related objects correctly.
 const char kEnableLeakDetection[] = "enable-leak-detection";
 
 // Encode binary layout test results (images, audio) using base64.
 const char kEncodeBinary[] = "encode-binary";
 
 // Request the render trees of pages to be dumped as text once they have
 // finished loading.
 const char kRunLayoutTest[] = "run-layout-test";
 
 // This makes us disable some web-platform runtime features so that we test
 // content_shell as if it was a stable release. It is only followed when
 // kRunLayoutTest is set. For the features' level, see
 // http://dev.chromium.org/blink/runtime-enabled-features.
 const char kStableReleaseMode[] = "stable-release-mode";
 
 }  // namespace switches