Temporarily re-introduce load-component-extension switch.

chrome/browser/extensions/extension_service.cc

Index: chrome/browser/extensions/extension_service.cc
diff --git a/chrome/browser/extensions/extension_service.cc b/chrome/browser/extensions/extension_service.cc
index 873462906484aa1d576d377cdb8593ac7825bb65..7a283b58138b0caa20f76fe9d913e34e5135b120 100644
--- a/chrome/browser/extensions/extension_service.cc
+++ b/chrome/browser/extensions/extension_service.cc
@@ -137,6 +137,10 @@ namespace {
 // Wait this many seconds after an extensions becomes idle before updating it.
 const int kUpdateIdleDelay = 5;
 
+// Comma-separated list of directories with extensions to load.
+// TODO(samuong): Remove this in M58 (see comment in ExtensionService::Init).
+const char kDeprecatedLoadComponentExtension[] = "load-component-extension";
+
 }  // namespace
 
 // ExtensionService.
@@ -439,6 +443,20 @@ void ExtensionService::Init() {
   LoadExtensionsFromCommandLineFlag(switches::kDisableExtensionsExcept);
   if (extensions_enabled_)
     LoadExtensionsFromCommandLineFlag(switches::kLoadExtension);
+  // ChromeDriver has no way of determining the Chrome version until after
+  // launch, so it needs to continue passing load-component-extension until it
+  // stops supporting Chrome 56 (when M58 is released). These extensions are
+  // loaded as regular extensions, not component extensions, and are thus safe.
+  // TODO(samuong): Remove this when we release Chrome 58 to stable channel.
+  if (command_line_->HasSwitch(switches::kEnableAutomation) &&
+      command_line_->HasSwitch(kDeprecatedLoadComponentExtension)) {
+    LOG(WARNING) << "Loading extension specified by "
+                    "--load-component-extension as a regular extension. "
+                    "Extensions specified by --load-component-extension will "
+                    "not be loaded starting in M58. Use --load-extension or "
+                    "--disable-extensions-except.";
+    LoadExtensionsFromCommandLineFlag(kDeprecatedLoadComponentExtension);
+  }
   EnabledReloadableExtensions();
   MaybeFinishShutdownDelayed();
   SetReadyAndNotifyListeners();