Modified OverviewMode's LabelButton bounds to cover the entire item.

ui/views/controls/button/label_button.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/views/controls/button/label_button.h"
 
 #include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "ui/gfx/animation/throb_animation.h"
 #include "ui/gfx/canvas.h"
@@ skipping 269 matching lines @@
     height = std::min(height, max_size_.height());
   return height;
 }
 
 void LabelButton::Layout() {
   gfx::HorizontalAlignment adjusted_alignment = GetHorizontalAlignment();
   if (base::i18n::IsRTL() && adjusted_alignment != gfx::ALIGN_CENTER)
     adjusted_alignment = (adjusted_alignment == gfx::ALIGN_LEFT) ?
         gfx::ALIGN_RIGHT : gfx::ALIGN_LEFT;
 
+  // By default, GetChildAreaBounds() ignores the top and bottom border, but we

[msw, 2015/02/06 21:24:26]

Flip around some of this code: GetChildAreaBounds shouldn't apply any border
insets (MenuButton and CredentialsItemView already rely on that behavior).

Instead have this code do something like:
  gfx::Rect child_area(GetChildAreaBounds());
  gfx::Rect label_area(child_area);

  gfx::Insets insets(GetInsets());
  child_area.Inset(insets);
  // Labels can paint over the vertical component of the border insets.
  label_area.Inset(insets.left(), 0, insets.right(), 0);

  gfx::Size image_size(image_->GetPreferredSize());
  image_size.SetToMin(child_area.size());

  // The label takes any remaining width after sizing the image, unless both
  // views are centered. In that case, using the tighter preferred label width
  // avoids wasted space within the label that would look like awkward padding.
  <REMOVE THE LAST LINE OF THE COMMENT...>
  gfx::Size label_size(label_area.size());

[Nina, 2015/02/09 16:35:09]

Done. The idea behind the way I had originally written it was to avoid having
the LabelButton subclass know the detail that its parent class only ignores the
vertical button padding.

+  // want the image to respect it.
+  gfx::Rect max_image_bounds = GetLocalBounds();
+  max_image_bounds.Inset(GetInsets());
   gfx::Rect child_area(GetChildAreaBounds());
-  child_area.Inset(GetInsets());
 
   gfx::Size image_size(image_->GetPreferredSize());
   image_size.SetToMin(child_area.size());
+  image_size.SetToMin(max_image_bounds.size());
 
   // The label takes any remaining width after sizing the image, unless both
   // views are centered. In that case, using the tighter preferred label width
   // avoids wasted space within the label that would look like awkward padding.
   // Labels can paint over the full button height, including the border height.
-  gfx::Size label_size(child_area.width(), height());
+  gfx::Size label_size(child_area.size());
   if (!image_size.IsEmpty() && !label_size.IsEmpty()) {
     label_size.set_width(std::max(child_area.width() -
         image_size.width() - image_label_spacing_, 0));
     if (adjusted_alignment == gfx::ALIGN_CENTER) {
       // Ensure multi-line labels paired with images use their available width.
       label_size.set_width(
           std::min(label_size.width(), label_->GetPreferredSize().width()));
     }
   }
 
   gfx::Point image_origin(child_area.origin());
   image_origin.Offset(0, (child_area.height() - image_size.height()) / 2);
   if (adjusted_alignment == gfx::ALIGN_CENTER) {
     const int spacing = (image_size.width() > 0 && label_size.width() > 0) ?
         image_label_spacing_ : 0;
     const int total_width = image_size.width() + label_size.width() +
         spacing;
     image_origin.Offset((child_area.width() - total_width) / 2, 0);
   } else if (adjusted_alignment == gfx::ALIGN_RIGHT) {
     image_origin.Offset(child_area.width() - image_size.width(), 0);
   }
 
-  gfx::Point label_origin(child_area.x(), 0);
+  gfx::Point label_origin(child_area.origin());

[msw, 2015/02/06 21:24:26]

Then change this to: gfx::Point label_origin(label_area.origin());

[Nina, 2015/02/09 16:35:09]

Done.

   if (!image_size.IsEmpty() && adjusted_alignment != gfx::ALIGN_RIGHT) {
     label_origin.set_x(image_origin.x() + image_size.width() +
         image_label_spacing_);
   }
 
   image_->SetBoundsRect(gfx::Rect(image_origin, image_size));
   label_->SetBoundsRect(gfx::Rect(label_origin, label_size));
 }
 
 const char* LabelButton::GetClassName() const {
   return kViewClassName;
 }
 
 scoped_ptr<LabelButtonBorder> LabelButton::CreateDefaultBorder() const {
   return make_scoped_ptr(new LabelButtonBorder(style_));
 }
 
 void LabelButton::SetBorder(scoped_ptr<Border> border) {
   border_is_themed_border_ = false;
   View::SetBorder(border.Pass());
   ResetCachedPreferredSize();
 }
 
 gfx::Rect LabelButton::GetChildAreaBounds() {
-  return GetLocalBounds();
+  gfx::Rect bounds = GetLocalBounds();

[msw, 2015/02/06 21:24:26]

Revert this to just return GetLocalBounds().

[Nina, 2015/02/09 16:35:09]

Done.

+  gfx::Insets insets = GetInsets();
+  bounds.Inset(insets.left(), 0, insets.right(), 0);
+  return bounds;
 }
 
 void LabelButton::OnPaint(gfx::Canvas* canvas) {
   View::OnPaint(canvas);
   Painter::PaintFocusPainter(this, canvas, focus_painter_.get());
 }
 
 void LabelButton::OnFocus() {
   View::OnFocus();
   // Typically the border renders differently when focused.
@@ skipping 146 matching lines @@
 }
 
 ui::NativeTheme::State LabelButton::GetForegroundThemeState(
     ui::NativeTheme::ExtraParams* params) const {
   GetExtraParams(params);
   return ui::NativeTheme::kHovered;
 }
 
 void LabelButton::ResetCachedPreferredSize() {
   cached_preferred_size_valid_ = false;
-  cached_preferred_size_= gfx::Size();
+  cached_preferred_size_ = gfx::Size();
 }
 
 }  // namespace views