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

content/shell/browser/layout_test/layout_test_devtools_frontend.cc

 // Copyright 2014 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/browser/layout_test/layout_test_devtools_frontend.h"
 
 #include "base/command_line.h"
 #include "base/json/json_reader.h"
 #include "base/json/json_writer.h"
 #include "base/path_service.h"
@@ skipping 34 matching lines @@
   if (!PathService::Get(base::DIR_EXE, &dir_exe)) {
     NOTREACHED();
     return GURL();
   }
 #if defined(OS_MACOSX)
   // On Mac, the executable is in
   // out/Release/Content Shell.app/Contents/MacOS/Content Shell.
   // We need to go up 3 directories to get to out/Release.
   dir_exe = dir_exe.AppendASCII("../../..");
 #endif
+  base::FilePath dev_tools_path;
   bool is_debug_dev_tools = base::CommandLine::ForCurrentProcess()->HasSwitch(
       switches::kDebugDevTools);
-  std::string folder = is_debug_dev_tools ? "debug/" : "";
-  base::FilePath dev_tools_path =
-      dir_exe.AppendASCII("resources/inspector/" + folder + "inspector.html");
+  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kCustomDevToolsFrontend)) {
+    dev_tools_path = base::CommandLine::ForCurrentProcess()->GetSwitchValuePath(
+        switches::kCustomDevToolsFrontend);
+  } else {
+    std::string folder = is_debug_dev_tools ? "debug/" : "";
+    dev_tools_path = dir_exe.AppendASCII("resources/inspector/" + folder);
+  }
 
-  GURL result = net::FilePathToFileURL(dev_tools_path);
+  GURL result =
+      net::FilePathToFileURL(dev_tools_path.AppendASCII("inspector.html"));
   std::string url_string =
       base::StringPrintf("%s?experiments=true", result.spec().c_str());
   if (is_debug_dev_tools)
     url_string += "&debugFrontend=true";
   return GURL(url_string);
 }
 
 void LayoutTestDevToolsFrontend::ReuseFrontend(const std::string& settings,
                                                const std::string frontend_url) {
   DisconnectFromTarget();
@@ skipping 59 matching lines @@
     base::TerminationStatus status) {
   BlinkTestController::Get()->DevToolsProcessCrashed();
 }
 
 void LayoutTestDevToolsFrontend::RenderFrameCreated(
     RenderFrameHost* render_frame_host) {
   BlinkTestController::Get()->HandleNewRenderFrameHost(render_frame_host);
 }
 
 }  // namespace content