Move StringToUpperASCII and LowerCaseEqualsASCII to the base namespace

Convert LowerCaseEqualsASCII to take StringPiece. In the current patch this is
generally a NOP but will allow me to delete the other 4 variants in a followup
(wanted to do that separately since that will require more review, since
callsites will be changed in nontrivial ways).

In some cases, LowerCaseEqualsASCII is called with a WebString, which no
longer is implicitly converted. I added base::string16(...) around such
calls to force the right conversion. It happened in these files:
  window_container_type.cc
  savable_resources.cc
  render_view_impl.cc
  blink_ax_tree_source.cc
  password_form_conversion_utils.cc
  translate_helper.cc
  chrome_render_view_observer.cc
  dom_serializer_browsertest.cc

R=jamesr@chromium.org

Review URL: https://codereview.chromium.org/448143008

Cr-Commit-Position: refs/heads/master@{#289312}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@289312 0039d316-1c4b-4281-b951-d872f2087c98


CrOS-Libchrome-Original-Commit: eee3522979ae33c9ddc7ec33c769b2c3f0a48320
diff --git a/base/files/file_path.cc b/base/files/file_path.cc
index a8b2713..2496e17 100644
--- a/base/files/file_path.cc
+++ b/base/files/file_path.cc
@@ -141,13 +141,14 @@
 
   for (size_t i = 0; i < arraysize(kCommonDoubleExtensions); ++i) {
     StringType extension(path, penultimate_dot + 1);
-    if (LowerCaseEqualsASCII(extension, kCommonDoubleExtensions[i]))
+    if (base::LowerCaseEqualsASCII(extension, kCommonDoubleExtensions[i]))
       return penultimate_dot;
   }
 
   StringType extension(path, last_dot + 1);
   for (size_t i = 0; i < arraysize(kCommonDoubleExtensionSuffixes); ++i) {
-    if (LowerCaseEqualsASCII(extension, kCommonDoubleExtensionSuffixes[i])) {
+    if (base::LowerCaseEqualsASCII(extension,
+                                   kCommonDoubleExtensionSuffixes[i])) {
       if ((last_dot - penultimate_dot) <= 5U &&
           (last_dot - penultimate_dot) > 1U) {
         return penultimate_dot;