fix text color of BlueButton on GTK-theme-mode Linux Aura.

ui/views/controls/button/label_button.cc

Index: ui/views/controls/button/label_button.cc
diff --git a/ui/views/controls/button/label_button.cc b/ui/views/controls/button/label_button.cc
index fd9d5641d5e38fca453140e5d9bbd386092723fb..00d00edef44501873354c13693a7bcb59aef84a0 100644
--- a/ui/views/controls/button/label_button.cc
+++ b/ui/views/controls/button/label_button.cc
@@ -365,7 +365,10 @@ void LabelButton::UpdateThemedBorder() {
 #if defined(OS_LINUX) && !defined(OS_CHROMEOS)
   views::LinuxUI* linux_ui = views::LinuxUI::instance();
   if (linux_ui) {
+    Border* default_border = label_button_border.get();
     SetBorder(linux_ui->CreateNativeBorder(this, label_button_border.Pass()));
+    // If we're using a system-themed border, make sure the text is legible.
+    label_->SetAutoColorReadabilityEnabled(border() != default_border);

[msw, 2014/05/29 19:52:23]

Should the label background color be initialized here? It only happens on
StateChanged for Linux Desktop, and otherwise this readability behavior might
use some default/uninitialized value. In testing, this seems to only apply
"readable" colors to the normal state after a hover.

   } else
 #endif
   {
@@ -376,6 +379,13 @@ void LabelButton::UpdateThemedBorder() {
 }
 
 void LabelButton::StateChanged() {
+  if (border_is_themed_border_) {
+    label_->SetBackgroundColor(GetNativeTheme()->GetSystemColor(

[msw, 2014/05/29 02:03:55]

Does this work right if gfx::IsInvertedColorScheme() adds a visible solid black
background to the button? (maybe that doesn't happen at all on Linux?)

[Evan Stade, 2014/05/29 19:04:45]

Do I need a Windows machine to test that? Is the bg black even when hovered for
inverted color schemes? Why are the inverted colors not piped through the
nativetheme?

I guess I can guard this with !gfx::IsInvertedColorScheme().

[msw, 2014/05/29 19:52:23]

Yeah, IsInvertedColorScheme is only supported on Windows for now, but I tested
this for you.
Yes, we draw a black rectangle under the label (but not covering the whole
button), regardless of the button state, so that the text is readable to those
with visibility needs.
The inverted color scheme support and design is abysmal and needs an overhaul,
along with the pattern of painting image assets here, rather than through
NativeTheme. We already need a LabelButton 2.0 :(
Yes, your CL as-is breaks the normal state text color for the Windows High
Contrast Black system theme (but only after the initial hover; see my other CL
comment above). Simply adding a !gfx::IsInvertedColorScheme() condition here
would be appropriate for now (it prevents the breakage this would otherwise
introduce).

+        state() == STATE_HOVERED ?
+            ui::NativeTheme::kColorId_ButtonHoverBackgroundColor :
+            ui::NativeTheme::kColorId_ButtonBackgroundColor));
+  }
+
   const gfx::Size previous_image_size(image_->GetPreferredSize());
   UpdateImage();
   const SkColor color = button_state_colors_[state()];