Rename blink::AtomicString::Lower() to DeprecatedLower().

third_party/WebKit/Source/platform/wtf/text/AtomicString.h

Index: third_party/WebKit/Source/platform/wtf/text/AtomicString.h
diff --git a/third_party/WebKit/Source/platform/wtf/text/AtomicString.h b/third_party/WebKit/Source/platform/wtf/text/AtomicString.h
index be86d59499fc6bd7e118141dfa674561bb7715a1..7d7de4f10b038203e52d7eb24a8423f4f2f2412f 100644
--- a/third_party/WebKit/Source/platform/wtf/text/AtomicString.h
+++ b/third_party/WebKit/Source/platform/wtf/text/AtomicString.h
@@ -167,7 +167,10 @@ class WTF_EXPORT AtomicString {
   // convert non-ASCII characters to ASCII characters. For example,
   // lower() for U+212A is 'k'.
   // This function is rarely used to implement web platform features.
-  AtomicString Lower() const;
+  // See crbug.com/627682.
+  // This function is deprecated. We should use LowerASCII(), or introduce
+  // LowerUnicode().
+  AtomicString DeprecatedLower() const;

[Yuta Kitamura, 2017/04/10 08:34:09]

I would slightly prefer renaming this to LowerUnicode(), since there
could be a valid use case where you really want to transform
Unicode characters.

But yeah, it's kinda strange to have LowerUnicode in *Atomic*String,
given how AtomicStrings are used (symbols, IDs, etc.), so I'm okay
with DeprecatedLower(), too.

[tkent, 2017/04/10 08:45:22]

IMO, we should apply the same approach to String too because if we renamed
Lower() to LowerUnicode() directly, we could not distinguish invalid usage of
Lower() and valid usage of Lower(). We should rename Lower() to
DeprecatedLower(), then should aim to remove it by replacing it to LowerASCII()
or LowerUnicode().

 
   // Returns a lowercase/uppercase version of the string.
   // These functions convert ASCII characters only.