[Chrome ELF] New NT registry API.

chrome/browser/chrome_elf_init_win.cc

Index: chrome/browser/chrome_elf_init_win.cc
diff --git a/chrome/browser/chrome_elf_init_win.cc b/chrome/browser/chrome_elf_init_win.cc
index c400196fc056a18d137bfdc847f35995457a9929..32decd01bf13d02fc3b1f8ebe6033cdf92000403 100644
--- a/chrome/browser/chrome_elf_init_win.cc
+++ b/chrome/browser/chrome_elf_init_win.cc
@@ -129,16 +129,23 @@ void AddFinchBlacklistToRegistry() {
       HKEY_CURRENT_USER, blacklist::kRegistryFinchListPath, KEY_SET_VALUE);
 
   std::map<std::string, std::string> params;
-  variations::GetVariationParams(kBrowserBlacklistTrialName, &params);
-
-  for (std::map<std::string, std::string>::iterator it = params.begin();
-       it != params.end();
-       ++it) {
-    std::wstring name = base::UTF8ToWide(it->first);
-    std::wstring val = base::UTF8ToWide(it->second);
-
-    finch_blacklist_registry_key.WriteValue(name.c_str(), val.c_str());
-  }
+  std::string value = variations::GetVariationParamValue(
+      kBrowserBlacklistTrialName, blacklist::kRegistryFinchListValueNameStr);
+  if (value.empty())
+    return;
+  std::wstring value_wcs = base::UTF8ToWide(value);

[robertshield, 2016/04/20 05:16:09]

prefer base::string16

[penny, 2016/05/28 01:34:22]

Done.  This base API explicitly returns a std::wstring, so that's what I was
using.  Also, it's converted from a std::string type, so it seemed cleaner to
match them.  I'm happy to make this base::string16 though, if you think it's
better here.

+
+  // The dll names are comma-separated in this param value.  We need to turn
+  // this into REG_MULTI_SZ format (double-null terminates).
+  // Note that the strings are wide character in registry.
+  std::vector<wchar_t> reg_buffer(value_wcs.begin(), value_wcs.end());

[robertshield, 2016/04/20 05:16:09]

I'm not sure you need to copy the dll names here. std::wstrings can contain
embedded null chars (with minimal gotchas, none of which apply to the code
below).

[penny, 2016/05/28 01:34:22]

Done.  TIL!  I didn't know you could embed null chars in a std::string  (and
still get the right size, etc).  Thanks! 

+  reg_buffer.push_back(L'\0');
+  reg_buffer.push_back(L'\0');
+  std::replace(reg_buffer.begin(), reg_buffer.end(), L',', L'\0');
+
+  finch_blacklist_registry_key.WriteValue(
+      blacklist::kRegistryFinchListValueName, reg_buffer.data(),
+      (reg_buffer.size() * sizeof(wchar_t)), REG_MULTI_SZ);
 }
 
 void BrowserBlacklistBeaconSetup() {