Plumb selection bounds as a single unit

public/platform/WebSelectionBounds.h

Index: public/platform/WebSelectionBounds.h
diff --git a/public/platform/WebSelectionBounds.h b/public/platform/WebSelectionBounds.h
new file mode 100644
index 0000000000000000000000000000000000000000..6678370d72b98269e399f666ab5f97c15ae87438
--- /dev/null
+++ b/public/platform/WebSelectionBounds.h
@@ -0,0 +1,39 @@
+// Copyright 2015 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 WebSelectionBounds_h
+#define WebSelectionBounds_h
+
+#include "public/platform/WebSelectionBound.h"
+
+namespace blink {
+
+// The endpoints for an active selection region.
+struct WebSelectionBounds {

[aelias_OOO_until_Jul13, 2015/03/12 19:29:16]

Just WebSelection might be a better name?

[jdduke (slow), 2015/03/16 18:15:41]

Sure. I hesitated to name it that to prevent confusion about it being a
reflection of the selection region, rather than selection itself, but I can
change it.

[jdduke (slow), 2015/03/16 18:19:20]

Maybe WebCompositedSelection?

+
+    WebSelectionBounds(const WebSelectionBound& start, const WebSelectionBound& end)
+        : start(start)
+        , end(end)
+        , isEditable(false)
+        , isEditableRegionEmpty(false)
+    {
+    }
+
+    // If the (empty) selection is an insertion point, |start| and |end| will be
+    // identical with type |Caret|.
+    // If the (non-empty) selection has mixed RTL/LTR text, |start| and |end|
+    // may share the same type, |SelectionLeft| or |SelectionRight|.
+    WebSelectionBound start;
+    WebSelectionBound end;
+
+    // Whether the selection region is editable.
+    bool isEditable;
+
+    // If the selection region is editable, whether it is empty.

[yosin_UTC9, 2015/03/13 02:06:37]

Q: Do you mean "region" as "range"?
It is confusing that |WebSelectionBound| have type |Caret| and
|WebSelectionBounds| doesn't have concept about collapsed selection.

[jdduke (slow), 2015/03/16 18:15:41]

Right, this isn't ideal. We should have sent the bounds as a unit before (as I'm
doing here) so that we could use a higher-level indicator for the selection
type, i.e., caret vs range, as with VisibleSelection. I'd look to move closer
toward that model, for now it's implicit that we have a caret if the bounds are
identical and they each have the type "Caret".

As a follow-up, I plan on removing the type metadata from the start/end region
up into this data structure, again, patterning it more closely to existing Blink
selection data structures.

+    bool isEditableRegionEmpty;
+};
+
+} // namespace blink
+
+#endif