Remove the use of WebRange in ContentDetector.

third_party/WebKit/public/web/WebSurroundingText.h

Index: third_party/WebKit/public/web/WebSurroundingText.h
diff --git a/third_party/WebKit/public/web/WebSurroundingText.h b/third_party/WebKit/public/web/WebSurroundingText.h
index 4b7af237d49b41fb24174dd6abf4523df264be3b..e5315c63efe7246bbeabf15495f47f4ae1f51b0b 100644
--- a/third_party/WebKit/public/web/WebSurroundingText.h
+++ b/third_party/WebKit/public/web/WebSurroundingText.h
@@ -72,10 +72,6 @@ public:
     // End offset of the initial text in the text content.
     BLINK_EXPORT size_t endOffsetInTextContent() const;
 
-    // Convert start/end positions in the content text string into a WebKit text
-    // range.
-    BLINK_EXPORT WebRange rangeFromContentOffsets(size_t startOffsetInContent, size_t endOffsetInContent);
-
 protected:
     std::unique_ptr<SurroundingText> m_private;
 };