Enforce license info in src/brave (fixes brave/brave-browser#9408)

Related upstream bug: https://bugs.chromium.org/p/chromium/issues/detail?id=39240

patches/tools-licenses.py.patch

@@ -1,12 +1,12 @@
 diff --git a/tools/licenses.py b/tools/licenses.py
-index 6405b31497a425c68b0486a2653071f23e515671..e957c14c924a7a405bf9e20f3c8e2ffc56ea1306 100755
+index 6405b31497a425c68b0486a2653071f23e515671..5402e94334b0ecb6ebcbefb9e4cd93b070eb5cbd 100755
 --- a/tools/licenses.py
 +++ b/tools/licenses.py
 @@ -35,6 +35,7 @@ else:
  _REPOSITORY_ROOT = os.path.abspath(os.path.dirname(os.path.dirname(__file__)))
  sys.path.insert(0, os.path.join(_REPOSITORY_ROOT, 'build/android/gyp'))
  from util import build_utils
-+from brave_license_helper import AddBraveCredits, BRAVE_THIRD_PARTY_DIRS
++from brave_license_helper import AddBraveCredits, BRAVE_THIRD_PARTY_DIRS, CheckBraveMissingLicense
  
  
  # Paths from the root of the tree to directories to skip.
@@ -28,3 +28,13 @@ index 6405b31497a425c68b0486a2653071f23e515671..e957c14c924a7a405bf9e20f3c8e2ffc
              # Add all subdirectories that are not marked for skipping.
              for dir in dirs:
                  dirpath = os.path.join(path, dir)
+@@ -663,7 +666,8 @@ def GenerateCredits(
+     for path in third_party_dirs:
+         try:
+             metadata = ParseDir(path, _REPOSITORY_ROOT)
+-        except LicenseError:
++        except LicenseError as e:
++            CheckBraveMissingLicense(target_os, path, e)
+             # TODO(phajdan.jr): Convert to fatal error (http://crbug.com/39240).
+             continue
+         if metadata['License File'] == NOT_SHIPPED:

script/brave_license_helper.py

@@ -9,6 +9,14 @@ BRAVE_THIRD_PARTY_DIRS = [
     'vendor',
 ]
 
+ANDROID_ONLY_PATHS = [
+    os.path.join('brave', 'components', 'brave_sync', 'extension', 'brave-sync-android'),
+]
+
+DESKTOP_ONLY_PATHS = [
+    os.path.join('brave', 'components', 'brave_sync', 'extension', 'brave-sync'),
+]
+
 
 def AddBraveCredits(prune_paths, special_cases, prune_dirs, additional_paths):
     # Exclude these specific paths from needing a README.chromium file.
@@ -149,3 +157,14 @@ def AddBraveCredits(prune_paths, special_cases, prune_dirs, additional_paths):
     additional_paths = tuple(additional_list)
 
     return (prune_dirs, additional_paths)
+
+
+def CheckBraveMissingLicense(target_os, path, error):
+    if path.startswith('brave'):
+        if (target_os == 'android'):
+            if path in DESKTOP_ONLY_PATHS:
+                return  # Desktop failures are not relevant on Android.
+        else:
+            if path in ANDROID_ONLY_PATHS:
+                return  # Android failures are not relevant on desktop.
+        raise error