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

third_party/WebKit/Source/devtools/scripts/npm_test.js

Index: third_party/WebKit/Source/devtools/scripts/npm_test.js
diff --git a/third_party/WebKit/Source/devtools/scripts/npm_test.js b/third_party/WebKit/Source/devtools/scripts/npm_test.js
index dc14020ce579554163b4242a725751546e6e976d..d9d0d3d059b8f8398fe133206ddec4ea949b40a1 100644
--- a/third_party/WebKit/Source/devtools/scripts/npm_test.js
+++ b/third_party/WebKit/Source/devtools/scripts/npm_test.js
@@ -210,21 +210,16 @@ function buildAndTest(buildDirectoryPath)
 function build(contentShellResourcesPath)
 {
     var devtoolsResourcesPath = path.resolve(contentShellResourcesPath, "inspector");
-    var copiedFrontendPath = path.resolve(devtoolsResourcesPath, "front_end");
-    var debugPath = path.resolve(devtoolsResourcesPath, "debug");
-    utils.removeRecursive(copiedFrontendPath);
-    utils.removeRecursive(debugPath);
-    utils.copyRecursive(SOURCE_PATH, devtoolsResourcesPath);
-    fs.renameSync(copiedFrontendPath, debugPath);
     var inspectorBackendCommandsPath = path.resolve(devtoolsResourcesPath, "InspectorBackendCommands.js");
     var supportedCSSPropertiesPath = path.resolve(devtoolsResourcesPath, "SupportedCSSProperties.js");
-    utils.copy(inspectorBackendCommandsPath, debugPath);
-    utils.copy(supportedCSSPropertiesPath, debugPath);
+    utils.copy(inspectorBackendCommandsPath, SOURCE_PATH);
+    utils.copy(supportedCSSPropertiesPath, SOURCE_PATH);
 }
 
 function runTests(buildDirectoryPath)
 {
     var testArgs = [
+        `--additional-drt-flag=--devtools-path=${SOURCE_PATH}`,
         "--additional-drt-flag=--debug-devtools",
         "--no-pixel-tests",
         "--build-directory",