brave-core/docs/devtools_frontend_patching.md

DevTools Frontend Patching

Adding a New File

1. Add your file in //brave/third_party/devtools-frontend/src/front_end/{path to your file}
2. Create (if it doesn't exist) sources.gni with //brave/third_party/devtools-frontend/src/front_end/{path to your file}
3. Create a patch in the corresponding BUILD.gn in //third_party/devtools-frontend/src
4. Add a reference to the compiled file in //brave/third_party/devtools-frontend/src/config/gni/sources.gni

How It Works

When chromium_src/third_party/devtools-frontend/src/third_party/typescript/ts_library.py detects a file starting with //brave, it copies this file to the corresponding upstream directory. When the compilation of the corresponding target is done, ts_library.py removes the copied file to preserve the upstream sources in their original state.

Patching an Existing File

1. Create a patch file in //brave/chromium_src/third_party/devtools-frontend/src/front_end/{path to the file you want to patch}.ts
2. Apply the patch after SomeClass declaration in the original file:

   import { PatchSomeClass } from './SomeFile.patch.js'; (SomeClass as any) = PatchSomeClass(SomeClass);
   

How It Works

When chromium_src/third_party/devtools-frontend/src/third_party/typescript/ts_library.py detects a chromium_src counterpart, it copies the file to the corresponding upstream directory (replacing .ts with .patch.ts). You don't need to add this file in sources.gni or BUILD.gn. Instead, you should import the {filename}.patch.js file (See step #2 above). chromium_src/third_party/devtools-frontend/src/scripts/build/generate_devtools_grd.py will automatically add the .patch.js file into the resource bundle.