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

chrome/browser/ui/libgtk2ui/native_theme_gtk2.cc

Index: chrome/browser/ui/libgtk2ui/native_theme_gtk2.cc
diff --git a/chrome/browser/ui/libgtk2ui/native_theme_gtk2.cc b/chrome/browser/ui/libgtk2ui/native_theme_gtk2.cc
index f47540de9a6c9166e46ab8cc751a20baf694c004..11dd5bdfebe4fdc74d9ae3c6e36be74947266eba 100644
--- a/chrome/browser/ui/libgtk2ui/native_theme_gtk2.cc
+++ b/chrome/browser/ui/libgtk2ui/native_theme_gtk2.cc
@@ -236,6 +236,16 @@ GdkColor NativeThemeGtk2::GetSystemGdkColor(ColorId color_id) const {
       return GetButtonStyle()->text[GTK_STATE_PRELIGHT];
     case kColorId_ButtonHoverBackgroundColor:
       return GetButtonStyle()->bg[GTK_STATE_PRELIGHT];
+    // TODO(estade): determine a more distinct color for the CallToAction

[msw, 2014/06/02 21:06:20]

How about using the existing button colors above (with the same values here),
and doing SetAutoColorReadabilityEnabled on the label to handle cases where the
system colors don't work? Perhaps that will typically yield white as
expected/spec'ed, and it seems like we ought to use readable versions of the
system colors anyway.

[Evan Stade, 2014/06/02 22:18:14]

I don't follow. This code just makes blue buttons look like normal buttons.
There's no other option right now, except to make blue buttons never be themed,
which looks way worse IMO.

[msw, 2014/06/02 22:39:44]

Yeah, I suggest (1) using readable versions of these normal button text colors.
We need readable colors because users with blue text colors won't be able to
read blue text on blue buttons.

I'm also suggesting (2) possibly removing these new color ids. I'm hoping that
we can just use the normal color ids (like kColorId_ButtonEnabledColor above)
everywhere and still get something legible and close to spec.

+    // buttons.
+    case kColorId_CallToActionButtonEnabledColor:

[msw, 2014/06/03 22:20:41]

Rename these kColorId_BlueButton*, or rename BlueButton CallToActionButton. I
like the more intent-related name, but consistency is more important until you
want to do a wider rename.

[Evan Stade, 2014/06/03 23:16:12]

Done.

This reminds me of the part of Earthworm Jim where a quiz show asks you "What
color is Jim's red gun?"

[msw, 2014/06/03 23:24:52]

FYI, you haven't uploaded the latest patch set with this change.

[Evan Stade, 2014/06/04 00:12:10]

Done.

+      return GetButtonStyle()->text[GTK_STATE_NORMAL];
+    case kColorId_CallToActionButtonDisabledColor:
+      return GetButtonStyle()->text[GTK_STATE_INSENSITIVE];
+    case kColorId_CallToActionButtonHighlightColor:
+      return GetButtonStyle()->base[GTK_STATE_SELECTED];
+    case kColorId_CallToActionButtonHoverColor:
+      return GetButtonStyle()->text[GTK_STATE_PRELIGHT];
 
     // Textfield
     case kColorId_TextfieldDefaultColor: