Apply "incognito" tint to dark mode toolbar buttons.

This is necessary because ThemeProperties::GetDefaultColor() is never actually
reached for COLOR_TOOLBAR_BUTTON_ICON (so the kGoogleGrey100 return in
GetIncognitoColor() was dead code).  ThemeService::GetDefaultColor()
unconditionally uses the tint, which was {-1, -1, -1} in dark mode after
http://crrev.com/688233 .  This approximately restores the behavior from before
that CL, when dark-mode was special-cased for TINT_BUTTONS to just return white.

Another way to solve this would be to remove this code from ThemeService, add
a "return kChromeIconGrey" to GetLightModeColor() for COLOR_TOOLBAR_BUTTON_ICON,
and add processing to browser_theme_pack.cc to compute an override color if the
theme specifies TINT_BUTTONS.  This would change HasCustomColor() to return true
"more accurately" -- i.e. only if the theme customizes the color, instead of
what it does now, which is to return true any time the tint is not a no-op.
Looking at callers of HasCustomColor(COLOR_TOOLBAR_BUTTON_ICON), they seem to
want it to return true in the dark/incognito case, so I've avoided this route
for now, although perhaps these callers could be updated (e.g. to check if the
returned color was non-default or just unconditionally use the returned color as
if it's "custom").

This does not apply the dark tinting to TINT_FRAME*, since doing so will cause
dark mode to darken the frame images of every theme that uses them without
explicitly setting a manual tint (i.e. almost all themes that use custom frame
images).  This is sort of an interesting effect, but would almost certainly be
considered "breaking" these themes.

Bug: 995681
Change-Id: I4dd8a7c24323b5a4caf24b3ad08188f73de028c9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1762943
Auto-Submit: Peter Kasting <pkasting@chromium.org>
Commit-Queue: Evan Stade <estade@chromium.org>
Reviewed-by: Evan Stade <estade@chromium.org>
Cr-Commit-Position: refs/heads/master@{#689157}

chrome/browser/themes/browser_theme_pack.cc

@@ -62,7 +62,7 @@ constexpr int kTallestFrameHeight = kTallestTabHeight + 19;
 // change default theme assets, if you need themes to recreate their generated
 // images (which are cached), or if you changed how missing values are
 // generated.
-const int kThemePackVersion = 70;
+const int kThemePackVersion = 71;
 
 // IDs that are in the DataPack won't clash with the positive integer
 // uint16_t. kHeaderID should always have the maximum value because we want the

chrome/browser/themes/theme_properties.cc

@@ -154,7 +154,6 @@ base::Optional<SkColor> GetIncognitoColor(int id) {
       return gfx::kGoogleGrey900;
     case ThemeProperties::COLOR_BOOKMARK_TEXT:
     case ThemeProperties::COLOR_TAB_TEXT:
-    case ThemeProperties::COLOR_TOOLBAR_BUTTON_ICON:
       return gfx::kGoogleGrey100;
     case ThemeProperties::COLOR_NTP_TEXT:
       return gfx::kGoogleGrey200;
@@ -255,16 +254,25 @@ color_utils::HSL ThemeProperties::GetDefaultTint(int id, bool incognito) {
          "equivalents and an appropriate |incognito| value.";
   // If you change these defaults, you must increment the version number in
   // browser_theme_pack.cc.
-  if (incognito) {
-    if (id == TINT_FRAME)
-      return {-1, 0.7, 0.075};  // #DEE1E6 -> kGoogleGrey900
-    if (id == TINT_FRAME_INACTIVE)
+
+  // TINT_BUTTONS is used by ThemeService::GetDefaultColor() for both incognito
+  // and dark mode, and so must be applied to both.
+  if ((id == TINT_BUTTONS) &&
+      (incognito ||
+       ui::NativeTheme::GetInstanceForNativeUi()->ShouldUseDarkColors()))
+    return {-1, 0.57, 0.9605};  // kChromeIconGrey -> kGoogleGrey100
+
+  // The frame tints are used only when parsing browser themes, and should not
+  // take dark mode into account, lest themes with custom frame images get those
+  // images unexpectedly modified just because the user is in dark mode.
+  if ((id == TINT_FRAME) && incognito)
+    return {-1, 0.7, 0.075};  // #DEE1E6 -> kGoogleGrey900
+  if (id == TINT_FRAME_INACTIVE) {
+    if (incognito)
       return {0.57, 0.65, 0.1405};  // #DEE1E6 -> kGoogleGrey800
-    if (id == TINT_BUTTONS)
-      return {-1, 0.57, 0.9605};  // kChromeIconGrey -> kGoogleGrey100
-  } else if (id == TINT_FRAME_INACTIVE) {
-    return {-1, -1, 0.642};  // #DEE1E6 -> #E7EAED
+    return {-1, -1, 0.642};         // #DEE1E6 -> #E7EAED
   }
+
   return {-1, -1, -1};
 }