Add new API for only moving the selection extent point.

public/web/WebLocalFrame.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef WebLocalFrame_h
 #define WebLocalFrame_h
 
 #include "WebFrame.h"
 
 namespace blink {
@@ skipping 49 matching lines @@
 
 
     // Scripting --------------------------------------------------------------
     // ONLY FOR TESTS: Forwards to executeScriptAndReturnValue, but sets a fake
     // UserGestureIndicator before execution.
     virtual v8::Handle<v8::Value> executeScriptAndReturnValueForTests(const WebScriptSource&) = 0;
 
     // Associates an isolated world with human-readable name which is useful for
     // extension debugging.
     virtual void setIsolatedWorldHumanReadableName(int worldID, const WebString&) = 0;
+
+
+    // Selection --------------------------------------------------------------
+
+    // Moves the selection extent point. This function does not allow the
+    // selection to collapse. If the new extent is set to the same position as
+    // the current base, this function will do nothing.
+    virtual void moveRangeSelectionExtent(const WebPoint&) = 0;
 };
 
 } // namespace blink
 
 #endif // WebLocalFrame_h