Add external extensions json source in proper mac location.

chrome/browser/extensions/external_pref_extension_loader.cc

Index: chrome/browser/extensions/external_pref_extension_loader.cc
diff --git a/chrome/browser/extensions/external_pref_extension_loader.cc b/chrome/browser/extensions/external_pref_extension_loader.cc
index 8d90ee7249c19adf2ae7bd746cc885ed8504427d..8b6192006fbff415a761311f640a4efe4d178e40 100644
--- a/chrome/browser/extensions/external_pref_extension_loader.cc
+++ b/chrome/browser/extensions/external_pref_extension_loader.cc
@@ -7,7 +7,9 @@
 #include "base/file_path.h"
 #include "base/file_util.h"
 #include "base/logging.h"
+#include "base/metrics/histogram.h"
 #include "base/path_service.h"
+#include "chrome/common/chrome_paths.h"
 #include "content/browser/browser_thread.h"
 #include "content/common/json_value_serializer.h"
 
@@ -34,8 +36,10 @@ DictionaryValue* ExtractPrefs(const FilePath& path,
 
 }  // namespace
 
-ExternalPrefExtensionLoader::ExternalPrefExtensionLoader(int base_path_key)
-    : base_path_key_(base_path_key) {
+ExternalPrefExtensionLoader::ExternalPrefExtensionLoader(int base_path_key,
+                                                         Options options)
+    : base_path_key_(base_path_key),
+      options_(options){
   CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 }
 
@@ -72,8 +76,18 @@ void ExternalPrefExtensionLoader::LoadOnFileThread() {
         base_path_.Append(FILE_PATH_LITERAL("external_extensions.json"));
 
     if (file_util::PathExists(json_file)) {
-      JSONFileValueSerializer serializer(json_file);
-      prefs.reset(ExtractPrefs(json_file, &serializer));
+      if (IsOptionSet(ENSURE_PATH_CONTROLLED_BY_ADMIN) &&
+          !file_util::IsPathControlledByAdmin(json_file)) {
+        LOG(ERROR) << "Can not read external extensions source.  The file "
+                   << json_file.value() << " and every directory in its path "
+                   << "must be owned by root, and not be writable by all "
+                   << "users. This restriction prevents unprivleged users "
+                   << "from making chrome install extensions on other users' "
+                   << "accounts.";
+      } else {
+        JSONFileValueSerializer serializer(json_file);
+        prefs.reset(ExtractPrefs(json_file, &serializer));
+      }
     }
   }
 
@@ -82,6 +96,16 @@ void ExternalPrefExtensionLoader::LoadOnFileThread() {
 
   prefs_.reset(prefs.release());
 
+  // We want to deprecate the external extensions file inside the app
+  // bundle on mac os.  Use a histogram to see how many extensions
+  // are installed in this way.  We can use this data to measure the
+  // effectiveness of asking developers to use the new path, or any
+  // automatic migration methods we implement.

[TVL, 2011/08/25 14:07:28]

fyi - if folks were modifying the bundle link this, they were breaking the code
signature on the app.  But nothing on the OS really checks this.

[Sam Kerner (Chrome), 2011/08/25 14:29:58]

  Mark mentioned that in the bug.  In order to figure out how we should migrate
away from the current setup, I would like to know more about this.  I think
someone mentioned that requests to read from the keychain would have extra
prompts.  Will these prompts happen every time while the file exists, or every
time the file is altered?  

+  if (base_path_key_ == chrome::DIR_DEPRICATED_EXTERNAL_EXTENSIONS) {
+    UMA_HISTOGRAM_COUNTS_100("Extensions.DepricatedExternalJsonCount",
+                             prefs_->size());

[asargent_no_longer_on_chrome, 2011/08/24 22:55:09]

Optional suggestion - do we want to also measure the count of extensions using
the new location? Then we could see the ratio of deprecated to new over time. 

[Sam Kerner (Chrome), 2011/08/25 14:04:37]

Good point.  Done.

+  }
+
   // If we have any records to process, then we must have
   // read the .json file.  If we read the .json file, then
   // we were should have set |base_path_|.