[devtools] load remote devtools frontend for non-hosted mode

R=bmeurer@chromium.org

Fixed: 1095988
Change-Id: I6ebbe3de665d308d0a30ede1c6c27e5745f484e9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2248626Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Andrey Kosyakov <caseq@chromium.org>
Commit-Queue: Andrey Kosyakov <caseq@chromium.org>
Commit-Queue: Yang Guo <yangguo@chromium.org>
Auto-Submit: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#780432}

chrome/browser/ui/webui/devtools_ui_data_source.cc

@@ -115,13 +115,20 @@ void DevToolsDataSource::StartDataRequest(
                             base::CompareCase::INSENSITIVE_ASCII));
     std::string path_under_bundled =
         path_without_params.substr(bundled_path_prefix.length());
+    GURL custom_devtools_frontend = GetCustomDevToolsFrontendURL();
+    if (!custom_devtools_frontend.is_valid()) {
+      // Fetch from packaged resources.
+      StartBundledDataRequest(path_under_bundled, std::move(callback));
+      return;
+    }
     if (GetCustomDevToolsFrontendURL().SchemeIsFile()) {
       // Fetch from file system.
       StartFileRequest(path_under_bundled, std::move(callback));
-    } else {
-      // Fetch from packaged resources.
-      StartBundledDataRequest(path_under_bundled, std::move(callback));
+      return;
     }
+    GURL remote_url(custom_devtools_frontend.spec() + path_under_bundled);
+    // Fetch from remote URL.
+    StartCustomDataRequest(remote_url, std::move(callback));
     return;
   }
 

chrome/browser/ui/webui/devtools_ui_data_source_unittest.cc

@@ -128,7 +128,7 @@ TEST_F(DevToolsUIDataSourceTest, TestDevToolsBundledURLWithQueryParam) {
   EXPECT_FALSE(data().empty());
 }
 
-TEST_F(DevToolsUIDataSourceTest, TestDevToolsBundledURLWithSwitch) {
+TEST_F(DevToolsUIDataSourceTest, TestDevToolsBundledFileURLWithSwitch) {
 #if defined(OS_WIN)
   const char* flag_value = "file://C:/tmp/";
 #else
@@ -143,6 +143,17 @@ TEST_F(DevToolsUIDataSourceTest, TestDevToolsBundledURLWithSwitch) {
   EXPECT_EQ(data(), "file: devtools_app.html");
 }
 
+TEST_F(DevToolsUIDataSourceTest, TestDevToolsBundledRemoteURLWithSwitch) {
+  const char* flag_value = "http://example.com/example/path/";
+  base::CommandLine::ForCurrentProcess()->AppendSwitchASCII(
+      switches::kCustomDevtoolsFrontend, flag_value);
+  const GURL path =
+      DevToolsUrl().Resolve(DevToolsBundledPath(kDevToolsUITestFrontEndUrl));
+  StartRequest(path.path());
+  EXPECT_TRUE(data_received());
+  EXPECT_EQ(data(), "url: http://example.com/example/path/devtools_app.html");
+}
+
 TEST_F(DevToolsUIDataSourceTest, TestDevToolsInvalidBundledURL) {
   const GURL path =
       DevToolsUrl().Resolve(DevToolsBundledPath("invalid_devtools_app.html"));