Bug 1218042 - part 2 - make the CompileDB backend follow the backend protocol; r=mshal

Calling CommonBackend.consume_object ensures that we process WebIDL and
IPDL files (and many other things) correctly.  Calling
CommonBackend.consume_finished ensures that the CompileDB backend gets
to see the unified bindings and protocol files that we generate, and add
those files to the compilation database.

python/mozbuild/mozbuild/compilation/database.py

@@ -37,15 +37,13 @@ class CompileDBBackend(CommonBackend):
 
 
     def consume_object(self, obj):
-        if isinstance(obj, UnifiedSources):
-            # For unified sources, only include the unified source file.
-            # Note that unified sources are never used for host sources.
-            for f in obj.unified_source_mapping:
-                flags = self._get_dir_flags(obj.objdir)
-                self._build_db_line(obj.objdir, self.environment, f[0],
-                                    obj.canonical_suffix, flags, False)
-        elif isinstance(obj, Sources) or isinstance(obj, HostSources) or \
-             isinstance(obj, GeneratedSources):
+        consumed = CommonBackend.consume_object(self, obj)
+
+        if consumed:
+            return True
+
+        if isinstance(obj, Sources) or isinstance(obj, HostSources) or \
+           isinstance(obj, GeneratedSources):
             # For other sources, include each source file.
             for f in obj.files:
                 flags = self._get_dir_flags(obj.objdir)
@@ -56,12 +54,40 @@ class CompileDBBackend(CommonBackend):
         return True
 
     def consume_finished(self):
+        CommonBackend.consume_finished(self)
+
         import json
         # Output the database (a JSON file) to objdir/compile_commands.json
         outputfile = os.path.join(self.environment.topobjdir, 'compile_commands.json')
         with self._write_file(outputfile) as jsonout:
             json.dump(self._db, jsonout, indent=0)
 
+    def _process_unified_sources(self, obj):
+        # For unified sources, only include the unified source file.
+        # Note that unified sources are never used for host sources.
+        for f in obj.unified_source_mapping:
+            flags = self._get_dir_flags(obj.objdir)
+            self._build_db_line(obj.objdir, self.environment, f[0],
+                                obj.canonical_suffix, flags, False)
+
+    def _handle_idl_manager(self, idl_manager):
+        pass
+
+    def _handle_ipdl_sources(self, ipdl_dir, sorted_ipdl_sources,
+                             unified_ipdl_cppsrcs_mapping):
+        flags = self._get_dir_flags(ipdl_dir)
+        for f in unified_ipdl_cppsrcs_mapping:
+            self._build_db_line(ipdl_dir, self.environment, f[0],
+                                '.cpp', flags, False)
+
+    def _handle_webidl_build(self, bindings_dir, unified_source_mapping,
+                             webidls, expected_build_output_files,
+                             global_define_files):
+        flags = self._get_dir_flags(bindings_dir)
+        for f in unified_source_mapping:
+            self._build_db_line(bindings_dir, self.environment, f[0],
+                                '.cpp', flags, False)
+
     def _get_dir_flags(self, directory):
         if directory in self._flags:
             return self._flags[directory]