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..15fd4776664169a5b2f9ed7b60ac6e71ffdce303 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"
@@ -222,6 +223,17 @@ bool IsCommandLineSwitchEnabled(const std::string& switch_name) {
   return false;
 }
 
+bool 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
 
 struct SimpleFeature::Mappings {
@@ -363,20 +375,9 @@ 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.

[not at google - send to devlin, 2015/04/02 14:31:57]

Do you know whether this is actually set outside of tests? It actually seems
like a pretty dodgy flag to be exposing to the chrome binary. It's worth looking
into, because if it's not, we should just remove command line support entirely
and make it in-memory (like add a ScopedWhitelist class which SimpleFeature
reads from).

[jackhou1, 2015/04/07 23:46:21]

The only non-test use is here:
https://code.google.com/p/chromium/codesearch#chromium/src/chrome/browser/ext...

The other reference is in chrome_content_browser_client.cc when the switch is
copied onto the command line of the renderer process.

rockot (who's sitting behind me this week) suggested turning tab capture into a
BehaviorFeature, then adding an interface to TestExtensionsClient to globally
whitelist an extension.

-      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))