DevTools: fix --custom-devtools-frontend=file:// for Windows

Fixed: 1028931
Change-Id: Ib26155ca9769495458f4fa0e1a5ba0bfc77b8e47
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1939288Reviewed-by: Andrey Kosyakov <caseq@chromium.org>
Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Commit-Queue: Dmitry Gozman <dgozman@chromium.org>
Auto-Submit: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#721607}

chrome/browser/ui/webui/devtools_ui_data_source.cc

@@ -23,6 +23,7 @@
 #include "content/public/browser/devtools_frontend_host.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/common/url_constants.h"
+#include "net/base/filename_util.h"
 #include "net/base/load_flags.h"
 #include "net/traffic_annotation/network_traffic_annotation.h"
 #include "services/network/public/cpp/resource_request.h"
@@ -302,7 +303,10 @@ void DevToolsDataSource::StartFileRequest(const std::string& path,
   base::FilePath base_path;
   GURL custom_devtools_frontend = GetCustomDevToolsFrontendURL();
   if (custom_devtools_frontend.SchemeIsFile()) {
-    base_path = base_path.AppendASCII(custom_devtools_frontend.GetContent());
+    if (!net::FileURLToFilePath(custom_devtools_frontend, &base_path)) {
+      std::move(callback).Run(CreateNotFoundResponse());
+      return;
+    }
   } else {
 #if BUILDFLAG(DEBUG_DEVTOOLS)
     // Use default path for unbundled files when debug_devtools=true

chrome/browser/ui/webui/devtools_ui_data_source_unittest.cc

@@ -9,6 +9,7 @@
 #include "base/bind.h"
 #include "base/memory/ref_counted_memory.h"
 #include "base/strings/strcat.h"
+#include "build/build_config.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/url_constants.h"
 #include "content/public/browser/url_data_source.h"
@@ -128,8 +129,13 @@ TEST_F(DevToolsUIDataSourceTest, TestDevToolsBundledURLWithQueryParam) {
 }
 
 TEST_F(DevToolsUIDataSourceTest, TestDevToolsBundledURLWithSwitch) {
+#if defined(OS_WIN)
+  const char* flag_value = "file://C:/tmp/";
+#else
+  const char* flag_value = "file://tmp/";
+#endif
   base::CommandLine::ForCurrentProcess()->AppendSwitchASCII(
-      switches::kCustomDevtoolsFrontend, "file://tmp/");
+      switches::kCustomDevtoolsFrontend, flag_value);
   const GURL path =
       DevToolsUrl().Resolve(DevToolsBundledPath(kDevToolsUITestFrontEndUrl));
   StartRequest(path.path());