Symlink debug folder instead of symlinking individual files

The original behavior of build_debug_applications.py was to traverse all
files recursively in the front_end folder and symlink each individual
file to the version in third_party/blink/renderer/devtools/front_end.

However, this requires rebuilding of Chrome when new files are added to
the application. After this CL, the developer experience is more
What-You-See-Is-What-You-Get.

This CL is also in preparation to remove the logic in C++-land to remove
the need for a separate debug folder. A follow-up CL will change the
behavior of `debug_devtools` to symlink directly into
out/[NAME]/resources/inspector, rather than an explicit sub-directory.

As a nice side-effect of this change, we are no longer symlinking the
debug folder for every version of the application. Previously, it would
iterate through all `application_names` and symlink the full debug
folder. This is time-consuming and did not provide any actual benefit.
Since we now symlink directly to the local version, we no longer need to
build the HTML files directly.

Bug: 986365
Change-Id: I7e54ac3af57e0a3941b88a46b71b3ddacd5664f2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1713344Reviewed-by: Erik Luo <luoe@chromium.org>
Commit-Queue: Tim van der Lippe <tvanderlippe@google.com>
Cr-Commit-Position: refs/heads/master@{#680518}

third_party/blink/renderer/devtools/.gitignore

@@ -18,4 +18,9 @@ npm-debug.log
 /front_end/protocol_externs.js
 package-lock.json
 .vscode
-/front_end/*/jsconfig.json
\ No newline at end of file
+/front_end/*/jsconfig.json
+
+# These are generated for build and would be put in the symlinked folder (thus this folder)
+front_end/InspectorBackendCommands.js
+front_end/SupportedCSSProperties.js
+front_end/accessibility/ARIAProperties.js
\ No newline at end of file

third_party/blink/renderer/devtools/BUILD.gn

@@ -1402,10 +1402,6 @@ if (debug_devtools) {
   action("build_debug_devtools") {
     script = "scripts/build/build_debug_applications.py"
 
-    deps = [
-      ":copy_generated_scripts",
-    ]
-
     inputs = all_devtools_files + application_templates
     outputs = [
       "$resources_out_debug_dir/devtools_app.html",
@@ -1418,16 +1414,17 @@ if (debug_devtools) {
       "$resources_out_debug_dir/worker_app.html",
     ]
 
-    args = devtools_applications + [
-             "--input_path",
-             rebase_path("front_end", root_build_dir),
-             "--output_path",
-             rebase_path(resources_out_debug_dir, root_build_dir),
-           ]
+    args = [
+      "--input_path",
+      rebase_path("front_end", root_build_dir),
+      "--output_path",
+      rebase_path(resources_out_debug_dir, root_build_dir),
+    ]
   }
 
   copy("copy_generated_scripts") {
     deps = [
+      ":build_debug_devtools",
       ":frontend_protocol_sources",
       ":supported_css_properties",
     ]

third_party/blink/renderer/devtools/scripts/build/build_debug_applications.py

@@ -25,28 +25,37 @@ def main(argv):
         input_path = argv[input_path_flag_index + 1]
         output_path_flag_index = argv.index('--output_path')
         output_path = argv[output_path_flag_index + 1]
-        application_names = argv[1:input_path_flag_index]
     except:
         print('Usage: %s app_1 app_2 ... app_N --input_path <input_path> --output_path <output_path>' % argv[0])
         raise
 
-    loader = modular_build.DescriptorLoader(input_path)
-    for app in application_names:
-        descriptors = loader.load_application(app)
-        builder = DebugBuilder(app, descriptors, input_path, output_path)
-        builder.build_app()
+    symlink_dir_or_copy(input_path, output_path)
 
 
-def symlink_or_copy_file(src, dest, safe=False):
-    if safe and path.exists(dest):
-        os.remove(dest)
+def symlink_dir_or_copy(src, dest):
     if hasattr(os, 'symlink'):
-        os.symlink(src, dest)
+        if path.exists(dest):
+            if os.path.islink(dest):
+                os.unlink(dest)
+            else:
+                shutil.rmtree(dest)
+        os.symlink(join(os.getcwd(), src), dest)
     else:
-        shutil.copy(src, dest)
+        for filename in os.listdir(src):
+            src = join(os.getcwd(), src, filename)
+            if os.path.isdir(src):
+                copy_dir(src, join(dest, filename))
+            else:
+                copy_file(src, join(dest, filename), safe=True)
+
+
+def copy_file(src, dest, safe=False):
+    if safe and path.exists(dest):
+        os.remove(dest)
+    shutil.copy(src, dest)
 
 
-def symlink_or_copy_dir(src, dest):
+def copy_dir(src, dest):
     if path.exists(dest):
         shutil.rmtree(dest)
     for src_dir, dirs, files in os.walk(src):
@@ -56,37 +65,7 @@ def symlink_or_copy_dir(src, dest):
         for name in files:
             src_name = join(os.getcwd(), src_dir, name)
             dest_name = join(dest_dir, name)
-            symlink_or_copy_file(src_name, dest_name)
-
-
-# Outputs:
-#   <app_name>.html as-is
-#   <app_name>.js as-is
-#   <module_name>/<all_files>
-class DebugBuilder(object):
-
-    def __init__(self, application_name, descriptors, application_dir, output_dir):
-        self.application_name = application_name
-        self.descriptors = descriptors
-        self.application_dir = application_dir
-        self.output_dir = output_dir
-
-    def app_file(self, extension):
-        return self.application_name + '.' + extension
-
-    def build_app(self):
-        if self.descriptors.has_html:
-            self._build_html()
-        for filename in os.listdir(self.application_dir):
-            src = join(os.getcwd(), self.application_dir, filename)
-            if os.path.isdir(src):
-                symlink_or_copy_dir(src, join(self.output_dir, filename))
-            else:
-                symlink_or_copy_file(src, join(self.output_dir, filename), safe=True)
-
-    def _build_html(self):
-        html_name = self.app_file('html')
-        symlink_or_copy_file(join(os.getcwd(), self.application_dir, html_name), join(self.output_dir, html_name), True)
+            copy_file(src_name, dest_name)
 
 
 if __name__ == '__main__':