Revert of Revert of DevTools: Introduce module initializers

Source/devtools/scripts/compile_frontend.py

Index: Source/devtools/scripts/compile_frontend.py
diff --git a/Source/devtools/scripts/compile_frontend.py b/Source/devtools/scripts/compile_frontend.py
index 632ce53652c1067619bf3126ea13983210790a66..0b1f1f228a8dd7d3e32887ca2592e2e731b4228b 100755
--- a/Source/devtools/scripts/compile_frontend.py
+++ b/Source/devtools/scripts/compile_frontend.py
@@ -36,9 +36,9 @@
 import sys
 import tempfile
 try:
+    import simplejson as json
+except ImportError:
     import json
-except ImportError:
-    import simplejson as json
 
 scripts_path = path.dirname(path.abspath(__file__))
 devtools_path = path.dirname(scripts_path)
@@ -57,8 +57,9 @@
 generate_protocol_externs.generate_protocol_externs(protocol_externs_file, path.join(devtools_path, "protocol.json"))
 
 jsmodule_name_prefix = "jsmodule_"
-js_modules_name = "frontend_modules.json"
+frontend_modules_name = "frontend_modules.json"
 runtime_module_name = "_runtime"
+module_initializer_name = "_module.js"
 
 
 def error_excepthook(exctype, value, traceback):
@@ -67,30 +68,11 @@
 sys.excepthook = error_excepthook
 
 try:
-    with open(path.join(scripts_path, js_modules_name), "rt") as js_modules_file:
+    with open(path.join(scripts_path, frontend_modules_name), "rt") as js_modules_file:
         modules = json.loads(js_modules_file.read())
 except:
-    print "ERROR: Failed to read %s" % js_modules_name
+    log_error("Failed to read %s" % frontend_modules_name)
     raise
-
-# `importScript` function must not be used in any files
-# except module headers. Refer to devtools.gyp file for
-# the module header list.
-allowed_import_statements_files = [
-    "console/ConsolePanel.js",
-    "elements/ElementsPanel.js",
-    "resources/ResourcesPanel.js",
-    "network/NetworkPanel.js",
-    "settings/SettingsScreen.js",
-    "sources/SourcesPanel.js",
-    "timeline/TimelinePanel.js",
-    "profiler/ProfilesPanel.js",
-    "audits/AuditsPanel.js",
-    "layers/LayersPanel.js",
-    "extensions/ExtensionServer.js",
-    "source_frame/SourceFrame.js",
-    "documentation/DocumentationView.js",
-]
 
 type_checked_jsdoc_tags_list = ["param", "return", "type", "enum"]
 
@@ -114,21 +96,26 @@
 def hasErrors(output):
     return re.search(error_warning_regex, output) != None
 
+
+def log_error(message):
+    print "ERROR: " + message
 
 def verify_importScript_usage():
     errors_found = False
     for module in modules:
-        for file_name in module['sources']:
-            if file_name in allowed_import_statements_files:
+        for file_name in module["sources"]:
+            if path.basename(file_name) == module_initializer_name:
+                log_error("Module initializer (%s) may not be listed among module's scripts; found in '%s'" % (module_initializer_name, module["name"]))
+                errors_found = True
                 continue
             try:
                 with open(path.join(devtools_frontend_path, file_name), "r") as sourceFile:
                     source = sourceFile.read()
                     if re.search(importscript_regex, source):
-                        print "ERROR: importScript function call is allowed in module header files only (found in %s)" % file_name
+                        log_error("importScript() call only allowed in module initializers (%s); found in %s" % (module_initializer_name, file_name))
                         errors_found = True
             except:
-                print "ERROR: Failed to access %s" % file_name
+                log_error("Failed to access %s" % file_name)
                 raise
     return errors_found
 
@@ -226,7 +213,7 @@
     for module in modules:
         for dependency in module["dependencies"]:
             if dependency in standalone_modules_by_name:
-                print "ERROR: Standalone module %s may not be present among the dependencies of %s" % (dependency, module["name"])
+                log_error("Standalone module '%s' may not be present among the dependencies of '%s'" % (dependency, module["name"]))
                 errors_found = True
 
 verify_standalone_modules()
@@ -243,7 +230,7 @@
         for source in module["sources"]:
             referencing_module = seen_files.get(source)
             if referencing_module:
-                print "ERROR: Duplicate use of %s in '%s' (previously seen in '%s')" % (source, name, referencing_module)
+                log_error("Duplicate use of %s in '%s' (previously seen in '%s')" % (source, name, referencing_module))
             seen_files[source] = name
 
     for module_name in standalone_modules_by_name: