[Omnibox] Elide omnibox text

ui/gfx/render_text.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.h"
 
 #include <limits.h>
 
 #include <algorithm>
 #include <climits>
@@ skipping 545 matching lines @@
   min_line_height_ = line_height;
   cached_bounds_and_offset_valid_ = false;
   lines_.clear();
   OnDisplayTextAttributeChanged();
 }
 
 void RenderText::SetElideBehavior(ElideBehavior elide_behavior) {
   // TODO(skanuj) : Add a test for triggering layout change.
   if (elide_behavior_ != elide_behavior) {
     elide_behavior_ = elide_behavior;
+    lines_.clear();

[msw, 2017/04/17 22:39:10]

Hmm, I'm a little surprised this isn't already handled [indirectly] via
OnDisplayTextAttributeChanged(). (presumably, when display text properties
change, we can't trust the result of the previous line breaking pass). Can you
check if removing this |lines_.clear();| statement and calling UpdateDisplayText
(perhaps indirectly, via EnsureLayout()) is sufficient? I'm guessing that you
don't need any RenderTextChanges, and the user is just somehow skipping a layout
pass after changing the elide behavior.

Otherwise, it might make sense to do |lines_.clear()| in
OnDisplayTextAttributeChanged. (Theoretically we can avoid clearing the lines if
we are switching between no eliding and fade eliding, but that's not a big
deal.)

[simonhong, 2017/04/17 23:21:43]

UpdateDisplayText() didn't handled it properly.
In RenderTextHarfBuzz::EnsureLayoutRunList(), UpdateDisplayText() is called.
Then, update_display_text_ and update_display_run_list_ are set to false.
After that, we lost the chance of clearing previous |lines_|.
Moved.

     OnDisplayTextAttributeChanged();
   }
 }
 
 void RenderText::SetDisplayRect(const Rect& r) {
   if (r != display_rect_) {
     display_rect_ = r;
     baseline_ = kInvalidBaseline;
     cached_bounds_and_offset_valid_ = false;
     lines_.clear();
@@ skipping 1120 matching lines @@
 
   for (; range_max < length; ++range_max)
     if (iter.IsEndOfWord(range_max) || iter.IsStartOfWord(range_max))
       break;
 
   return range.is_reversed() ? Range(range_max, range_min)
                              : Range(range_min, range_max);
 }
 
 }  // namespace gfx