Allow the IncreasedContrastThemeSupplier to Opt-Out of Most Incognito Colors

Previously, the IncreasedContrastThemeSupplier bypassed most of the
incognito colors. This worked fine as the colors it did specify worked
with non-incognito colors in incognito.

http://crrev.com/719713 removed this bypass, resulting in incognito
colors applied to the IncreasedContrastThemeSupplier and white-on-white
text as well as light-on-white controls.

This change reintroduces this opt-out as a workaround.

BUG=1045630

Change-Id: Ib83172fbd90559bc72e94e850591ee66cd4ad4e9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2024468
Commit-Queue: Robert Liao <robliao@chromium.org>
Commit-Queue: Peter Kasting <pkasting@chromium.org>
Auto-Submit: Robert Liao <robliao@chromium.org>
Reviewed-by: Peter Kasting <pkasting@chromium.org>
Cr-Commit-Position: refs/heads/master@{#735723}

chrome/browser/themes/custom_theme_supplier.cc

@@ -57,3 +57,7 @@ base::RefCountedMemory* CustomThemeSupplier::GetRawData(
 bool CustomThemeSupplier::HasCustomImage(int id) const {
   return false;
 }
+
+bool CustomThemeSupplier::CanUseIncognitoColors() const {
+  return true;
+}

chrome/browser/themes/custom_theme_supplier.h

@@ -74,6 +74,11 @@ class CustomThemeSupplier
   // Whether this theme provides an image for |id|.
   virtual bool HasCustomImage(int id) const;
 
+  // Returns whether or not the default incognito colors can be used with this
+  // theme. This is a workaround for the IncreasedContrastThemeSupplier that
+  // doesn't supply all the colors it should (http://crbug.com/1045630).
+  virtual bool CanUseIncognitoColors() const;
+
  protected:
   virtual ~CustomThemeSupplier();
 

chrome/browser/themes/increased_contrast_theme_supplier.cc

@@ -47,3 +47,7 @@ bool IncreasedContrastThemeSupplier::GetColor(int id, SkColor* color) const {
   }
   return false;
 }
+
+bool IncreasedContrastThemeSupplier::CanUseIncognitoColors() const {
+  return false;
+}

chrome/browser/themes/increased_contrast_theme_supplier.h

@@ -15,6 +15,7 @@ class IncreasedContrastThemeSupplier : public CustomThemeSupplier {
   explicit IncreasedContrastThemeSupplier(bool is_dark_mode);
 
   bool GetColor(int id, SkColor* color) const override;
+  bool CanUseIncognitoColors() const override;
 
  protected:
   ~IncreasedContrastThemeSupplier() override;

chrome/browser/themes/theme_service.cc

@@ -1126,7 +1126,9 @@ bool ThemeService::UsingCustomTheme() const {
 bool ThemeService::UseIncognitoColor(int id) const {
   // Incognito is disabled for any non-ignored custom theme colors so they apply
   // atop a predictable state.
-  return !UsingCustomTheme() || ShouldIgnoreThemeSupplier(id, true);
+  return ShouldIgnoreThemeSupplier(id, true) ||
+         (!UsingCustomTheme() &&
+          (!theme_supplier_ || theme_supplier_->CanUseIncognitoColors()));
 }
 
 bool ThemeService::UseDarkModeColors() const {