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 6a5bece485df46b7ccc9db8ef21c5d62a521ba93..d37712c3ec267d5eb51172980411ea55115e2073 100644
--- a/extensions/common/features/simple_feature.cc
+++ b/extensions/common/features/simple_feature.cc
@@ -11,6 +11,7 @@
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/debug/alias.h"
+#include "base/macros.h"
 #include "base/sha1.h"
 #include "base/stl_util.h"
 #include "base/strings/string_number_conversions.h"
@@ -363,20 +364,9 @@ 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) &&
+      !IsWhitelistedByCommandLine(extension_id)) {
+    return CreateAvailability(NOT_FOUND_IN_WHITELIST, type);
   }
 
   if (!MatchesManifestLocation(location))
@@ -622,4 +612,17 @@ bool SimpleFeature::IsValidExtensionId(const std::string& extension_id) {
   return (extension_id.length() == 32);
 }
 
+// static
+bool SimpleFeature::IsWhitelistedByCommandLine(
+    const std::string& extension_id) {
+  // A singleton copy of the --whitelisted-extension-id so that we don't need to
+  // copy it from the CommandLine each time.
+  CR_DEFINE_STATIC_LOCAL(
+      std::string, whitelisted_extension_id,
+      (base::CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
+          switches::kWhitelistedExtensionID)));
+  return !whitelisted_extension_id.empty() &&
+         whitelisted_extension_id == extension_id;
+}
+
 }  // namespace extensions