Expand WTF::StringView's API to be more like StringPiece.

third_party/WebKit/Source/wtf/text/WTFString.h

Index: third_party/WebKit/Source/wtf/text/WTFString.h
diff --git a/third_party/WebKit/Source/wtf/text/WTFString.h b/third_party/WebKit/Source/wtf/text/WTFString.h
index 8d01437df9b2314a390c9d56513ad6af83386194..4b809023cf568ab24898a5bd38a0b0ebb586e7ce 100644
--- a/third_party/WebKit/Source/wtf/text/WTFString.h
+++ b/third_party/WebKit/Source/wtf/text/WTFString.h
@@ -343,9 +343,6 @@ public:
     String left(unsigned len) const { return substring(0, len); }
     String right(unsigned len) const { return substring(length() - len, len); }
 
-    StringView createView() const { return StringView(impl()); }
-    StringView createView(unsigned offset, unsigned length) const { return StringView(impl(), offset, length); }
-
     // Returns a lowercase/uppercase version of the string
     String lower() const;
     String upper() const;
@@ -667,6 +664,13 @@ inline void String::prependTo(Vector<UChar, inlineCapacity>& result, unsigned po
     }
 }
 
+inline StringView::StringView(const String& string)
+    : StringView(string, 0, string.length()) {}
+inline StringView::StringView(const String& string, unsigned offset, unsigned length)
+    : StringView(string.impl(), offset, length) {}
+inline StringView::StringView(const String& string, unsigned offset)
+    : StringView(string.impl(), offset) {}

[Yuta Kitamura, 2016/05/27 04:47:41]

Having inline definitions of StringView here looks strange.
If some files just include StringView.h but not WTFString.h,
uses of these constructors there will not get inlined
and you might end up weird link errors.

How about reversing the include dependency, i.e. remove
#include "wtf/StringView.h" from here and add #include
"WTFString.h" in StringView.h, and move the inline
definitions there? I think that's more natural and
intuitive.

This also applies other inlined constructors.

+
 // StringHash is the default hash for String
 template<typename T> struct DefaultHash;
 template<> struct DefaultHash<String> {