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 732779d4c7ba0ca0d33e76fe75ffab240b1f5a03..ec0c59294f862aae7953720160f274f76f6b43a1 100644
--- a/chrome/browser/extensions/extension_service.cc
+++ b/chrome/browser/extensions/extension_service.cc
@@ -439,6 +439,12 @@ void ExtensionService::Init() {
   LoadExtensionsFromCommandLineFlag(switches::kDisableExtensionsExcept);
   if (extensions_enabled_)
     LoadExtensionsFromCommandLineFlag(switches::kLoadExtension);
+  // TODO(samuong): Remove this when ChromeDriver stops supporting Chrome 56.
+  // 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.

[Devlin, 2017/02/14 20:44:41]

Clarify that this only loads the extension as a regular extension, *not* as a
component extension, and is thus safe.

[Devlin, 2017/02/14 20:44:41]

ETA?

[samuong, 2017/02/14 21:22:49]

Done. ChromeDriver supports the current and previous stable releases, so we
won't need this flag in Chrome 58+. I've updated the comment to mention this.

+  if (command_line_->HasSwitch(switches::kEnableAutomation))

[Devlin, 2017/02/14 20:44:41]

Maybe something like:
if (command_line_->HasSwitch(switches::kEnableAutomation) &&
    command_line_->HasSwitch(kLoadComponentExtension)) {
  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 M<NN>. Use --load-extension or
--disable-extensions-except."
  LoadExtensionFromCommandLineFlag(kLoadComponentExtension);
}

[samuong, 2017/02/14 21:22:49]

Done.

+    LoadExtensionsFromCommandLineFlag(switches::kLoadComponentExtension);
   EnabledReloadableExtensions();
   MaybeFinishShutdownDelayed();
   SetReadyAndNotifyListeners();