Add new API for only moving the selection extent point.

public/web/WebFrame.h

Index: public/web/WebFrame.h
diff --git a/public/web/WebFrame.h b/public/web/WebFrame.h
index 0250a19423b095f1649b85f50ec182784bb24d27..557c129f48b48b9fc4dd75789ae1dd888c3e3986 100644
--- a/public/web/WebFrame.h
+++ b/public/web/WebFrame.h
@@ -454,6 +454,9 @@ public:
 
     virtual void selectRange(const WebRange&) = 0;
 
+    // Move the selection extent point.
+    virtual void moveSelectionExtent(const WebPoint&) = 0;

[mlamouri (slow - plz ping), 2014/10/15 12:13:51]

Can't you define that in public/web/WebLocalFrame.h instead of WebFrame.h? Given
that you Chromium CL is using a WebLocalFrame and it's not defined in
WebRemoteFrame, it sounds like you could by pass entirely
WebFrame/WebRemoteFrame here.

[jdduke (slow), 2014/10/15 17:49:47]

I think it would be a little odd to restrict this method to WebLocalFrame, when
all of the related methods are declared in WebFrame.

Looking at the naming, I wonder if |moveRangeSelectionExtent| fits better with
the existing scheme, maybe not?

[christiank, 2014/10/17 14:30:24]

Sure, I'll move it to WebLocalFrame and rename it to moveRangeSelectionExtent
while at it.

+
     // Move the current selection to the provided window point/points. If the
     // current selection is editable, the new selection will be restricted to
     // the root editable element.