Make gfx::Rect class operations consistently mutate the class they are called on.

ui/gfx/render_text_win.cc

 // Copyright (c) 2012 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.
 
 #include "ui/gfx/render_text_win.h"
 
 #include <algorithm>
 
 #include "base/i18n/break_iterator.h"
 #include "base/i18n/rtl.h"
@@ skipping 363 matching lines @@
     if (intersection.IsValid()) {
       DCHECK(!intersection.is_reversed());
       ui::Range range_x(GetGlyphXBoundary(run, intersection.start(), false),
                         GetGlyphXBoundary(run, intersection.end(), false));
       Rect rect(range_x.GetMin(), 0, range_x.length(), run->font.GetHeight());
       // Center the rect vertically in the display area.
       rect.Offset(0, (display_rect().height() - rect.height()) / 2);
       rect.set_origin(ToViewPoint(rect.origin()));
       // Union this with the last rect if they're adjacent.
       if (!bounds.empty() && rect.SharesEdgeWith(bounds.back())) {
-        rect = rect.Union(bounds.back());
+        rect.Union(bounds.back());
         bounds.pop_back();
       }
       bounds.push_back(rect);
     }
   }
   return bounds;
 }
 
 size_t RenderTextWin::TextIndexToLayoutIndex(size_t index) const {
   if (!obscured())
@@ skipping 433 matching lines @@
   size_t position = LayoutIndexToTextIndex(run->range.end());
   position = IndexOfAdjacentGrapheme(position, CURSOR_BACKWARD);
   return SelectionModel(position, CURSOR_FORWARD);
 }
 
 RenderText* RenderText::CreateInstance() {
   return new RenderTextWin;
 }
 
 }  // namespace gfx