Move StringToUpperASCII and LowerCaseEqualsASCII to the base namespace

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

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=289312

[brettw, 2014-08-07 20:31:17]

James: Since you expressed an opinion of how strings should be done, you get
this!

Please check string_util.cc carefully, and also look at the .cc files mentioned
in the description. The rest of the changes are just search-and-replace.

[jamesr, 2014-08-07 20:38:25]

lgtm

https://codereview.chromium.org/448143008/diff/20001/chrome/browser/local_dis...
File chrome/browser/local_discovery/device_description.cc (right):

https://codereview.chromium.org/448143008/diff/20001/chrome/browser/local_dis...
chrome/browser/local_discovery/device_description.cc:62: if
(base::LowerCaseEqualsASCII(key, kPrivetTxtKeyVersion)) {
for a file like this, would it be better to just have a

using base::LowerCaseEqualsASCII;

in this .cc ?

[brettw, 2014-08-13 16:23:45]

Committed patchset #6 manually as 289312.