MacViews: Use Mac's "Constrained Window Button" style for Button::STYLE_BUTTON LabelButtons

STYLE_BUTTON is typically the button used for dialog buttons
(OK/Cancel/etc.). On Chrome Mac, dialogs have switched from Cocoa
buttons to a "Constrained Window" button style. This is a button with a
gradient and lots of shadows. Use it as the default dialog button style
for MacViews, by porting the current Quartz implementation to Skia.

To integrate into toolkit-views, the approach is similar to how
libgtk2ui::Gtk2Border is used for LabelButtons on Linux Aura. However,
unlike Gtk2Border, we don't want to replace the asset-based `BlueButton`
style with a themed style. (On Mac, the `BlueLabelButton` currently used
for Cocoa dialgos is a port of the toolkit-views BlueButton).

Introduce ui/views/style/platform_style.h. Currently with:
  CreateLabelButtonBorder(ButtonStyle) -> LabelButtonBorder
  CreateThemedLabelButtonBorder(LabelButton*) -> Border

The first provides the default style as a LabelButtonBorder, which
subclasses of LabelButton can use to customize border insets.

The second provides a way for Gtk2Border to entirely re-theme the button
border provided by a subclass, the way it currently does for BlueButton.

Then, since LabelButtonBorder can paint either with assets or vector
drawing routines, a subclass `LabelButtonAssetBorder` is added to
encapsulate borders drawn with assets.

Screenshots at http://crbug.com/506150#c3

BUG=506150

Review URL: https://codereview.chromium.org/1217163002

Cr-Commit-Position: refs/heads/master@{#340407}

3 files changed, 4 insertions, 4 deletions

diff --git a/ash/system/chromeos/session/logout_button_tray.cc b/ash/system/chromeos/session/logout_button_tray.cc
index 084af0a..1b7addc 100644
--- a/ash/system/chromeos/session/logout_button_tray.cc
+++ b/ash/system/chromeos/session/logout_button_tray.cc
@@ -71,8 +71,8 @@ LogoutButton::LogoutButton(views::ButtonListener* listener)
   for (size_t state = 0; state < views::Button::STATE_COUNT; ++state)
     SetTextColor(static_cast<views::Button::ButtonState>(state), SK_ColorWHITE);
 
-  scoped_ptr<views::LabelButtonBorder> border(
-      new views::LabelButtonBorder(views::Button::STYLE_TEXTBUTTON));
+  scoped_ptr<views::LabelButtonAssetBorder> border(
+      new views::LabelButtonAssetBorder(views::Button::STYLE_TEXTBUTTON));
   border->SetPainter(false, views::Button::STATE_NORMAL,
       views::Painter::CreateImageGridPainter(kLogoutButtonNormalImages));
   border->SetPainter(false, views::Button::STATE_HOVERED,
diff --git a/ash/system/tray/tray_popup_label_button_border.cc b/ash/system/tray/tray_popup_label_button_border.cc
index bcbf39f..693fce1 100644
--- a/ash/system/tray/tray_popup_label_button_border.cc
+++ b/ash/system/tray/tray_popup_label_button_border.cc
@@ -15,7 +15,7 @@
 namespace ash {
 
 TrayPopupLabelButtonBorder::TrayPopupLabelButtonBorder()
-    : LabelButtonBorder(views::Button::STYLE_TEXTBUTTON) {
+    : LabelButtonAssetBorder(views::Button::STYLE_TEXTBUTTON) {
   const int kTrayPopupLabelButtonBorderImagesNormal[] = {
       IDR_AURA_TRAY_POPUP_LABEL_BUTTON_BORDER,
       IDR_AURA_TRAY_POPUP_LABEL_BUTTON_NORMAL_BACKGROUND,
diff --git a/ash/system/tray/tray_popup_label_button_border.h b/ash/system/tray/tray_popup_label_button_border.h
index bb06444..1afca11 100644
--- a/ash/system/tray/tray_popup_label_button_border.h
+++ b/ash/system/tray/tray_popup_label_button_border.h
@@ -13,7 +13,7 @@ namespace ash {
 
 // A border for label buttons that paints a vertical separator in normal state
 // and a custom hover effect in hovered or pressed state.
-class TrayPopupLabelButtonBorder : public views::LabelButtonBorder {
+class TrayPopupLabelButtonBorder : public views::LabelButtonAssetBorder {
  public:
   TrayPopupLabelButtonBorder();
   ~TrayPopupLabelButtonBorder() override;