bindings: Fix generate_v8_context_snapshot_external_references.py for the great Blink mv.

- Pass -snake-case-generated-files flag if snake_case_source_files
- Apply to_snake_case to pre-defined INCLUDES too.

Bug: 760462
Change-Id: Iacb84b7fb895160cf4791c4570c31d1bd0c62cbc
Reviewed-on: https://chromium-review.googlesource.com/672027Reviewed-by: Hitoshi Yoshida <peria@chromium.org>
Commit-Queue: Kent Tamura <tkent@chromium.org>
Cr-Commit-Position: refs/heads/master@{#502960}

third_party/WebKit/Source/bindings/modules/v8/BUILD.gn

@@ -143,6 +143,9 @@ action("generate_v8_context_snapshot_external_references") {
     "--target-component",
     "modules",
   ]
+  if (snake_case_source_files) {
+    args += [ "--snake-case-generated-files" ]
+  }
 
   deps = [
     "//third_party/WebKit/Source/bindings/core:interfaces_info_individual_core",

third_party/WebKit/Source/bindings/scripts/generate_v8_context_snapshot_external_references.py

@@ -6,6 +6,7 @@
 
 import argparse
 import os
+import posixpath
 
 from code_generator import initialize_jinja_env
 from idl_reader import IdlReader
@@ -197,10 +198,20 @@ class ExternalReferenceTableGenerator(object):
         header_name = 'V8ContextSnapshotExternalReferences.h'
         if self._opts.snake_case_generated_files:
             header_name = 'v8_context_snapshot_external_references.h'
+        include_files = list(self._include_files)
+        # TODO(tkent): Update INCLUDES after the great mv, and remove the
+        # following block. crbug.com/760462
+        if self._opts.snake_case_generated_files:
+            include_files = []
+            for include in self._include_files:
+                dirname, basename = posixpath.split(include)
+                name, ext = posixpath.splitext(basename)
+                include_files.append(posixpath.join(
+                    dirname, utilities.to_snake_case(name) + ext))
         return {
             'class': 'V8ContextSnapshotExternalReferences',
             'interfaces': interfaces,
-            'include_files': sorted(list(self._include_files)),
+            'include_files': sorted(include_files),
             'this_include_header_name': header_name,
         }