Add initial support for API versioning (see #3836)

- Generated files are now created when running cef_create_projects or
  the new version_manager.py tool. These files are still created in the
  cef/ source tree (same location as before) but Git ignores them due to
  the generated .gitignore file.
- API hashes are committed to Git as a new cef_api_versions.json file.
  This file is used for both code generation and CEF version calculation
  (replacing the previous usage of cef_api_hash.h for this purpose).
  It will be updated by the CEF admin before merging breaking API
  changes upstream.
- As an added benefit to the above, contributor PRs will no longer
  contain generated code that is susceptible to frequent merge conflicts.
- From a code generation perspective, the main difference is that we now
  use versioned structs (e.g. cef_browser_0_t instead of cef_browser_t)
  on the libcef (dll/framework) side. Most of the make_*.py tool changes
  are related to supporting this.
- From the client perspective, you can now define CEF_API_VERSION in the
  project configuration (or get CEF_EXPERIMENTAL by default). This
  define will change the API exposed in CEF’s include/ and include/capi
  header files. All client-side targets including libcef_dll_wrapper
  will need be recompiled when changing this define.
- Examples of the new API-related define usage are provided in
  cef_api_version_test.h, api_version_test_impl.cc and
  api_version_unittest.cc.

To test:
- Run `ceftests --gtest_filter=ApiVersionTest.*`
- Add `cef_api_version=13300` to GN_DEFINES. Re-run configure, build and
  ceftests steps.
- Repeat with 13301, 13302, 13303 (all supported test versions).

tools/make_distrib.py

@@ -6,6 +6,7 @@ from __future__ import absolute_import
 from __future__ import print_function
 from bazel_util import bazel_substitute, bazel_last_error, bazel_set_quiet
 from cef_version import VersionFormatter
+from clang_util import clang_format_inplace
 from date_util import *
 from exec_util import exec_cmd
 from file_util import *
@@ -226,7 +227,12 @@ def transfer_doxyfile(dst_dir, quiet):
       sys.stdout.write('Creating Doxyfile file.\n')
 
 
-def transfer_gypi_files(src_dir, gypi_paths, gypi_path_prefix, dst_dir, quiet):
+def transfer_gypi_files(src_dir,
+                        gypi_paths,
+                        gypi_path_prefix,
+                        dst_dir,
+                        quiet,
+                        format=False):
   """ Transfer files from one location to another. """
   for path in gypi_paths:
     src = os.path.join(src_dir, path)
@@ -235,6 +241,11 @@ def transfer_gypi_files(src_dir, gypi_paths, gypi_path_prefix, dst_dir, quiet):
     make_dir(dst_path, quiet)
     copy_file(src, dst, quiet)
 
+    # Apply clang-format for C/C++ files.
+    if format and os.path.splitext(dst)[1][1:] in ('c', 'cc', 'cpp', 'h'):
+      print(dst)
+      clang_format_inplace(dst)
+
 
 def extract_toolchain_cmd(build_dir,
                           exe_name,
@@ -925,17 +936,19 @@ if mode == 'standard' or mode == 'minimal':
   transfer_gypi_files(cef_dir, cef_paths2['includes_wrapper'], \
                       'include/', include_dir, options.quiet)
   transfer_gypi_files(cef_dir, cef_paths['autogen_cpp_includes'], \
-                      'include/', include_dir, options.quiet)
+                      'include/', include_dir, options.quiet, format=True)
   transfer_gypi_files(cef_dir, cef_paths['autogen_capi_includes'], \
-                      'include/', include_dir, options.quiet)
+                      'include/', include_dir, options.quiet, format=True)
 
   # Transfer generated include files.
   generated_includes = [
+      'cef_api_versions.h',
       'cef_color_ids.h',
       'cef_command_ids.h',
       'cef_config.h',
       'cef_pack_resources.h',
       'cef_pack_strings.h',
+      'cef_version.h',
   ]
   for include in generated_includes:
     # Debug and Release build should be the same so grab whichever exists.
@@ -953,7 +966,7 @@ if mode == 'standard' or mode == 'minimal':
   transfer_gypi_files(cef_dir, cef_paths2['libcef_dll_wrapper_sources_common'], \
                       'libcef_dll/', libcef_dll_dir, options.quiet)
   transfer_gypi_files(cef_dir, cef_paths['autogen_client_side'], \
-                      'libcef_dll/', libcef_dll_dir, options.quiet)
+                      'libcef_dll/', libcef_dll_dir, options.quiet, format=True)
 
   if mode == 'standard' or mode == 'minimal':
     # transfer additional files