Cache --whitelisted-extension-id in SimpleFeature.

extensions/common/features/simple_feature.cc

Index: extensions/common/features/simple_feature.cc
diff --git a/extensions/common/features/simple_feature.cc b/extensions/common/features/simple_feature.cc
index 7d1e06e35b11dffe0a7f4b469fc35bc61cb60e96..f363766b5f8988d6a7ac76e10ec52d9998b3c180 100644
--- a/extensions/common/features/simple_feature.cc
+++ b/extensions/common/features/simple_feature.cc
@@ -11,6 +11,7 @@
 #include "base/command_line.h"
 #include "base/debug/alias.h"
 #include "base/lazy_instance.h"
+#include "base/macros.h"
 #include "base/sha1.h"
 #include "base/stl_util.h"
 #include "base/strings/string_number_conversions.h"
@@ -344,20 +345,10 @@ Feature::Availability SimpleFeature::IsAvailableToManifest(
   if (component_extensions_auto_granted_ && location == Manifest::COMPONENT)
     return CreateAvailability(IS_AVAILABLE, type);
 
-  if (!whitelist_.empty()) {
-    if (!IsIdInWhitelist(extension_id)) {
-      // TODO(aa): This is gross. There should be a better way to test the
-      // whitelist.
-      base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
-      if (!command_line->HasSwitch(switches::kWhitelistedExtensionID))
-        return CreateAvailability(NOT_FOUND_IN_WHITELIST, type);
-
-      std::string whitelist_switch_value =
-          base::CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
-              switches::kWhitelistedExtensionID);
-      if (extension_id != whitelist_switch_value)
-        return CreateAvailability(NOT_FOUND_IN_WHITELIST, type);
-    }
+  if (!whitelist_.empty() && !IsIdInWhitelist(extension_id) &&
+      (whitelisted_extension_id().empty() ||

[tapted, 2015/03/31 04:46:07]

hm - two function calls isn't quite as nice.. 

If it's true that an empty extension ID might get here, then maybe instead of
whitelisted_extension_id() returning a string, have

bool IsWhitelistedByCommandLine(const std::string& extension_id);

That probably reads better regardless :/

[jackhou1, 2015/03/31 05:28:22]

Done.

+       extension_id != whitelisted_extension_id())) {
+    return CreateAvailability(NOT_FOUND_IN_WHITELIST, type);
   }
 
   if (!MatchesManifestLocation(location))
@@ -583,4 +574,13 @@ Feature::Availability SimpleFeature::CheckDependencies(
   return CreateAvailability(IS_AVAILABLE);
 }
 
+// static
+const std::string& SimpleFeature::whitelisted_extension_id() {
+  CR_DEFINE_STATIC_LOCAL(
+      std::string, whitelisted_extension_id,
+      (base::CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
+          switches::kWhitelistedExtensionID)));
+  return whitelisted_extension_id;
+}
+
 }  // namespace extensions