Revert "Added access operator to color mixers."

This reverts commit 1d267524.

Reason for revert: Suespect that this broke the build on Windows.

Original change's description:
> Added access operator to color mixers.
> 
> Added the access operator to the color mixer class, updated existing
> code and tests. Changed AddMixer() to return a mixer by reference.
> 
> Bug: 1887666
> Change-Id: I2ae180f77d73e3ce4567d061b5505d920677c450
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1910521
> Commit-Queue: Peter Kasting <pkasting@chromium.org>
> Reviewed-by: Peter Kasting <pkasting@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#714528}

TBR=pkasting@chromium.org,tluk@chromium.org

Change-Id: I7eae3b7e1824b31adaa04c5e998c883da05eea96
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1887666
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1911709Reviewed-by: James MacLean <wjmaclean@chromium.org>
Commit-Queue: James MacLean <wjmaclean@chromium.org>
Cr-Commit-Position: refs/heads/master@{#714543}

chrome/browser/themes/browser_theme_pack.cc

@@ -1035,7 +1035,7 @@ void BrowserThemePack::AddCustomThemeColorMixers(
   }
   if (theme_colors.empty())
     return;
-  provider->AddMixer().AddSet({kColorSetCustomTheme, std::move(theme_colors)});
+  provider->AddMixer()->AddSet({kColorSetCustomTheme, std::move(theme_colors)});
 }
 
 // private:

chrome/browser/themes/browser_theme_pack_unittest.cc

@@ -741,10 +741,10 @@ TEST_F(BrowserThemePackTest, TestCreateColorMixersOmniboxNoValues) {
   // Tests to make sure that existing colors within the color provider are not
   // overwritten or lost in the absence of any user provided theme values.
   ui::ColorProvider provider;
-  provider.AddMixer().AddSet({ui::kColorSetTest0,
-                              {{kColorToolbar, SK_ColorRED},
-                               {kColorOmniboxText, SK_ColorGREEN},
-                               {kColorOmniboxBackground, SK_ColorBLUE}}});
+  provider.AddMixer()->AddSet({ui::kColorSetTest0,
+                               {{kColorToolbar, SK_ColorRED},
+                                {kColorOmniboxText, SK_ColorGREEN},
+                                {kColorOmniboxBackground, SK_ColorBLUE}}});
   theme_pack().AddCustomThemeColorMixers(&provider);
   EXPECT_EQ(SK_ColorRED, provider.GetColor(kColorToolbar));
   EXPECT_EQ(SK_ColorGREEN, provider.GetColor(kColorOmniboxText));
@@ -755,10 +755,10 @@ TEST_F(BrowserThemePackTest, TestCreateColorMixersOmniboxPartialValues) {
   // Tests to make sure that only provided theme values are replicated into the
   // color provider.
   ui::ColorProvider provider;
-  provider.AddMixer().AddSet({ui::kColorSetTest0,
-                              {{kColorToolbar, SK_ColorRED},
-                               {kColorOmniboxText, SK_ColorGREEN},
-                               {kColorOmniboxBackground, SK_ColorBLUE}}});
+  provider.AddMixer()->AddSet({ui::kColorSetTest0,
+                               {{kColorToolbar, SK_ColorRED},
+                                {kColorOmniboxText, SK_ColorGREEN},
+                                {kColorOmniboxBackground, SK_ColorBLUE}}});
   std::string color_json = R"({ "toolbar": [0, 20, 40],
                                 "omnibox_text": [60, 80, 100] })";
   LoadColorJSON(color_json);
@@ -772,10 +772,10 @@ TEST_F(BrowserThemePackTest, TestCreateColorMixersOmniboxAllValues) {
   // Tests to make sure that all available colors are properly loaded into the
   // color provider.
   ui::ColorProvider provider;
-  provider.AddMixer().AddSet({ui::kColorSetTest0,
-                              {{kColorToolbar, SK_ColorRED},
-                               {kColorOmniboxText, SK_ColorGREEN},
-                               {kColorOmniboxBackground, SK_ColorBLUE}}});
+  provider.AddMixer()->AddSet({ui::kColorSetTest0,
+                               {{kColorToolbar, SK_ColorRED},
+                                {kColorOmniboxText, SK_ColorGREEN},
+                                {kColorOmniboxBackground, SK_ColorBLUE}}});
   std::string color_json = R"({ "toolbar": [0, 20, 40],
                                 "omnibox_text": [60, 80, 100],
                                 "omnibox_background": [120, 140, 160] })";

chrome/browser/ui/views/omnibox/omnibox_color_mixer.cc

@@ -13,47 +13,55 @@
 #include "ui/gfx/color_utils.h"
 
 void AddOmniboxColorMixer(ui::ColorProvider* provider, bool high_contrast) {
-  ui::ColorMixer& mixer = provider->AddMixer();
+  ui::ColorMixer* mixer = provider->AddMixer();
   const float minimum_contrast =
       high_contrast ? 6.0f : color_utils::kMinimumReadableContrastRatio;
 
   // Omnibox background colors.
-  mixer[kColorOmniboxBackground].AddTransform(ui::GetResultingPaintColor(
-      ui::FromTransformInput(), ui::FromInputColor(kColorToolbar)));
-  mixer[kColorOmniboxBackgroundHovered].AddTransform(ui::BlendTowardMaxContrast(
-      ui::FromResultColor(kColorOmniboxBackground), 0x0A));
+  mixer->AddRecipe(kColorOmniboxBackground)
+      .AddTransform(ui::GetResultingPaintColor(
+          ui::FromTransformInput(), ui::FromInputColor(kColorToolbar)));
+  mixer->AddRecipe(kColorOmniboxBackgroundHovered)
+      .AddTransform(ui::BlendTowardMaxContrast(
+          ui::FromResultColor(kColorOmniboxBackground), 0x0A));
 
   // Omnibox text colors.
-  mixer[kColorOmniboxText].AddTransform(ui::GetResultingPaintColor(
-      ui::FromTransformInput(), ui::FromResultColor(kColorOmniboxBackground)));
+  mixer->AddRecipe(kColorOmniboxText)
+      .AddTransform(ui::GetResultingPaintColor(
+          ui::FromTransformInput(),
+          ui::FromResultColor(kColorOmniboxBackground)));
   {
-    auto& selected_text = mixer[kColorOmniboxResultsTextSelected].AddTransform(
-        ui::FromResultColor(kColorOmniboxText));
+    auto& selected_text =
+        mixer->AddRecipe(kColorOmniboxResultsTextSelected)
+            .AddTransform(ui::FromResultColor(kColorOmniboxText));
     if (high_contrast)
       selected_text.AddTransform(ui::ContrastInvert(ui::FromTransformInput()));
   }
-  mixer[kColorOmniboxSelectedKeyword].AddTransform(
-      ui::SelectBasedOnDarkInput(ui::FromResultColor(kColorOmniboxBackground),
-                                 ui::FromColor(gfx::kGoogleGrey100),
-                                 ui::FromResultColor(kColorOmniboxResultsUrl)));
+  mixer->AddRecipe(kColorOmniboxSelectedKeyword)
+      .AddTransform(ui::SelectBasedOnDarkInput(
+          ui::FromResultColor(kColorOmniboxBackground),
+          ui::FromColor(gfx::kGoogleGrey100),
+          ui::FromResultColor(kColorOmniboxResultsUrl)));
 
   // Bubble outline colors.
-  mixer[kColorOmniboxBubbleOutline].AddTransform(ui::SelectBasedOnDarkInput(
-      ui::FromResultColor(kColorOmniboxBackground),
-      ui::FromColor(gfx::kGoogleGrey100),
-      ui::FromColor(SkColorSetA(gfx::kGoogleGrey900, 0x24))));
-  mixer[kColorOmniboxBubbleOutlineExperimentalKeywordMode].AddTransform(
-      ui::FromResultColor(kColorOmniboxSelectedKeyword));
+  mixer->AddRecipe(kColorOmniboxBubbleOutline)
+      .AddTransform(ui::SelectBasedOnDarkInput(
+          ui::FromResultColor(kColorOmniboxBackground),
+          ui::FromColor(gfx::kGoogleGrey100),
+          ui::FromColor(SkColorSetA(gfx::kGoogleGrey900, 0x24))));
+  mixer->AddRecipe(kColorOmniboxBubbleOutlineExperimentalKeywordMode)
+      .AddTransform(ui::FromResultColor(kColorOmniboxSelectedKeyword));
 
   // Results background colors.
-  mixer[kColorOmniboxResultsBackground].AddTransform(
-      ui::GetColorWithMaxContrast(ui::FromResultColor(kColorOmniboxText)));
-  mixer[kColorOmniboxResultsBackgroundHovered].AddTransform(
-      ui::BlendTowardMaxContrast(
+  mixer->AddRecipe(kColorOmniboxResultsBackground)
+      .AddTransform(
+          ui::GetColorWithMaxContrast(ui::FromResultColor(kColorOmniboxText)));
+  mixer->AddRecipe(kColorOmniboxResultsBackgroundHovered)
+      .AddTransform(ui::BlendTowardMaxContrast(
           ui::FromResultColor(kColorOmniboxResultsBackground),
           gfx::kGoogleGreyAlpha200));
-  mixer[kColorOmniboxResultsBackgroundSelected].AddTransform(
-      ui::BlendTowardMaxContrast(
+  mixer->AddRecipe(kColorOmniboxResultsBackgroundSelected)
+      .AddTransform(ui::BlendTowardMaxContrast(
           ui::GetColorWithMaxContrast(
               ui::FromResultColor(kColorOmniboxResultsTextSelected)),
           gfx::kGoogleGreyAlpha300));
@@ -66,11 +74,12 @@ void AddOmniboxColorMixer(ui::ColorProvider* provider, bool high_contrast) {
           ui::DeriveDefaultIconColor(ui::FromResultColor(text_id)),
           ui::FromResultColor(background_id), base::nullopt, minimum_contrast);
     };
-    mixer[kColorOmniboxResultsIcon].AddTransform(
-        results_icon(kColorOmniboxText, kColorOmniboxResultsBackground));
-    mixer[kColorOmniboxResultsIconSelected].AddTransform(
-        results_icon(kColorOmniboxResultsTextSelected,
-                     kColorOmniboxResultsBackgroundSelected));
+    mixer->AddRecipe(kColorOmniboxResultsIcon)
+        .AddTransform(
+            results_icon(kColorOmniboxText, kColorOmniboxResultsBackground));
+    mixer->AddRecipe(kColorOmniboxResultsIconSelected)
+        .AddTransform(results_icon(kColorOmniboxResultsTextSelected,
+                                   kColorOmniboxResultsBackgroundSelected));
   }
 
   // Dimmed text colors.
@@ -86,14 +95,16 @@ void AddOmniboxColorMixer(ui::ColorProvider* provider, bool high_contrast) {
                                   base::nullopt, minimum_contrast),
           minimum_contrast);
     };
-    mixer[kColorOmniboxResultsTextDimmed].AddTransform(
-        blend_with_clamped_contrast(kColorOmniboxText,
-                                    kColorOmniboxResultsBackgroundHovered));
-    mixer[kColorOmniboxResultsTextDimmedSelected].AddTransform(
-        blend_with_clamped_contrast(kColorOmniboxResultsTextSelected,
-                                    kColorOmniboxResultsBackgroundSelected));
-    mixer[kColorOmniboxTextDimmed].AddTransform(blend_with_clamped_contrast(
-        kColorOmniboxText, kColorOmniboxBackgroundHovered));
+    mixer->AddRecipe(kColorOmniboxResultsTextDimmed)
+        .AddTransform(blend_with_clamped_contrast(
+            kColorOmniboxText, kColorOmniboxResultsBackgroundHovered));
+    mixer->AddRecipe(kColorOmniboxResultsTextDimmedSelected)
+        .AddTransform(blend_with_clamped_contrast(
+            kColorOmniboxResultsTextSelected,
+            kColorOmniboxResultsBackgroundSelected));
+    mixer->AddRecipe(kColorOmniboxTextDimmed)
+        .AddTransform(blend_with_clamped_contrast(
+            kColorOmniboxText, kColorOmniboxBackgroundHovered));
   }
 
   // Results URL colors.
@@ -106,10 +117,10 @@ void AddOmniboxColorMixer(ui::ColorProvider* provider, bool high_contrast) {
                                      ui::FromColor(gfx::kGoogleBlue900)),
           minimum_contrast);
     };
-    mixer[kColorOmniboxResultsUrl].AddTransform(
-        url_color(kColorOmniboxResultsBackgroundHovered));
-    mixer[kColorOmniboxResultsUrlSelected].AddTransform(
-        url_color(kColorOmniboxResultsBackgroundSelected));
+    mixer->AddRecipe(kColorOmniboxResultsUrl)
+        .AddTransform(url_color(kColorOmniboxResultsBackgroundHovered));
+    mixer->AddRecipe(kColorOmniboxResultsUrlSelected)
+        .AddTransform(url_color(kColorOmniboxResultsBackgroundSelected));
   }
 
   // Security chip colors.
@@ -125,11 +136,12 @@ void AddOmniboxColorMixer(ui::ColorProvider* provider, bool high_contrast) {
                   ui::FromResultColor(kColorOmniboxBackgroundHovered),
                   base::nullopt, minimum_contrast));
         };
-    mixer[kColorOmniboxSecurityChipDangerous].AddTransform(
-        security_chip_color(ui::FromColor(gfx::kGoogleRed600)));
-    mixer[kColorOmniboxSecurityChipSecure].AddTransform(security_chip_color(
-        ui::DeriveDefaultIconColor(ui::FromResultColor(kColorOmniboxText))));
+    mixer->AddRecipe(kColorOmniboxSecurityChipDangerous)
+        .AddTransform(security_chip_color(ui::FromColor(gfx::kGoogleRed600)));
+    mixer->AddRecipe(kColorOmniboxSecurityChipSecure)
+        .AddTransform(security_chip_color(ui::DeriveDefaultIconColor(
+            ui::FromResultColor(kColorOmniboxText))));
   }
-  mixer[kColorOmniboxSecurityChipDefault].AddTransform(
-      ui::FromResultColor(kColorOmniboxSecurityChipSecure));
+  mixer->AddRecipe(kColorOmniboxSecurityChipDefault)
+      .AddTransform(ui::FromResultColor(kColorOmniboxSecurityChipSecure));
 }

ui/color/color_mixer.cc

@@ -4,6 +4,8 @@
 
 #include "ui/color/color_mixer.h"
 
+#include "base/containers/adapters.h"
+#include "base/stl_util.h"
 #include "ui/color/color_recipe.h"
 #include "ui/gfx/color_palette.h"
 
@@ -18,16 +20,17 @@ ColorMixer& ColorMixer::operator=(ColorMixer&&) noexcept = default;
 
 ColorMixer::~ColorMixer() = default;
 
-ColorRecipe& ColorMixer::operator[](ColorId id) {
-  DCHECK_COLOR_ID_VALID(id);
-  return recipes_[id];
-}
-
 void ColorMixer::AddSet(ColorSet&& set) {
   DCHECK(FindSetWithId(set.id) == sets_.cend());
   sets_.push_front(std::move(set));
 }
 
+ColorRecipe& ColorMixer::AddRecipe(ColorId id) {
+  DCHECK_COLOR_ID_VALID(id);
+  DCHECK(!base::Contains(recipes_, id));
+  return recipes_[id];
+}
+
 SkColor ColorMixer::GetInputColor(ColorId id) const {
   DCHECK_COLOR_ID_VALID(id);
   for (const auto& set : sets_) {

ui/color/color_mixer.h

@@ -39,14 +39,16 @@ class COMPONENT_EXPORT(COLOR) ColorMixer {
   ColorMixer& operator=(ColorMixer&&) noexcept;
   ~ColorMixer();
 
-  // Adds a recipe for |id| if it does not exist.
-  ColorRecipe& operator[](ColorId id);
-
   // Adds |set| to |sets_|.  |set| must not have the same ID as any previously
   // added sets, though it may contain colors with the same IDs as colors in
   // those sets; in such cases, the last-added set takes priority.
   void AddSet(ColorSet&& set);
 
+  // Adds a recipe for |id|, which must not already have an existing recipe.
+  // Returns a non-const ref to allow chaining calls to
+  // ColorRecipe::AddTransform().
+  ColorRecipe& AddRecipe(ColorId id);
+
   // Returns the input color for |id|.  First searches all |sets_| in reverse
   // order; if not found, asks the previous mixer for the result color.  If
   // there is no previous mixer, returns gfx::kPlaceholderColor.

ui/color/color_mixer_unittest.cc

@@ -27,10 +27,10 @@ TEST(ColorMixerTest, AddSet) {
   EXPECT_EQ(SK_ColorGREEN, mixer.GetResultColor(kColorTest0));
 }
 
-// Tests that the recipe returned by operator[] is respected by the mixer.
-TEST(ColorMixerTest, AccessOperator) {
+// Tests that the recipe returned by AddRecipe() is respected by the mixer.
+TEST(ColorMixerTest, AddRecipe) {
   ColorMixer mixer;
-  mixer[kColorTest0].AddTransform(FromColor(SK_ColorGREEN));
+  mixer.AddRecipe(kColorTest0).AddTransform(FromColor(SK_ColorGREEN));
   EXPECT_EQ(SK_ColorGREEN, mixer.GetResultColor(kColorTest0));
 }
 
@@ -86,8 +86,8 @@ TEST(ColorMixerTest, GetInputColorPreviousMixer) {
 TEST(ColorMixerTest, GetInputColorIgnoresRecipe) {
   ColorMixer mixer;
   mixer.AddSet({kColorSetTest0, {{kColorTest0, SK_ColorGREEN}}});
-  mixer[kColorTest0].AddTransform(
-      GetColorWithMaxContrast(FromTransformInput()));
+  mixer.AddRecipe(kColorTest0)
+      .AddTransform(GetColorWithMaxContrast(FromTransformInput()));
   EXPECT_EQ(SK_ColorGREEN, mixer.GetInputColor(kColorTest0));
 }
 
@@ -97,8 +97,8 @@ TEST(ColorMixerTest, GetInputColorIgnoresRecipe) {
 TEST(ColorMixerTest, GetInputColorRespectsRecipePreviousMixer) {
   ColorMixer mixer0;
   mixer0.AddSet({kColorSetTest0, {{kColorTest0, SK_ColorGREEN}}});
-  mixer0[kColorTest0].AddTransform(
-      GetColorWithMaxContrast(FromTransformInput()));
+  mixer0.AddRecipe(kColorTest0)
+      .AddTransform(GetColorWithMaxContrast(FromTransformInput()));
   ColorMixer mixer1(&mixer0);
   mixer1.AddSet({kColorSetTest1, {{kColorTest1, SK_ColorRED}}});
   EXPECT_EQ(color_utils::GetColorWithMaxContrast(SK_ColorGREEN),
@@ -169,8 +169,8 @@ TEST(ColorMixerTest, GetOriginalColorFromSetPreviousMixer) {
 TEST(ColorMixerTest, GetOriginalColorFromSetIgnoresRecipe) {
   ColorMixer mixer;
   mixer.AddSet({kColorSetTest0, {{kColorTest0, SK_ColorGREEN}}});
-  mixer[kColorTest0].AddTransform(
-      GetColorWithMaxContrast(FromTransformInput()));
+  mixer.AddRecipe(kColorTest0)
+      .AddTransform(GetColorWithMaxContrast(FromTransformInput()));
   EXPECT_EQ(SK_ColorGREEN,
             mixer.GetOriginalColorFromSet(kColorTest0, kColorSetTest0));
 }
@@ -181,8 +181,8 @@ TEST(ColorMixerTest, GetOriginalColorFromSetIgnoresRecipe) {
 TEST(ColorMixerTest, GetOriginalColorFromSetIgnoresRecipePreviousMixer) {
   ColorMixer mixer0;
   mixer0.AddSet({kColorSetTest0, {{kColorTest0, SK_ColorGREEN}}});
-  mixer0[kColorTest0].AddTransform(
-      GetColorWithMaxContrast(FromTransformInput()));
+  mixer0.AddRecipe(kColorTest0)
+      .AddTransform(GetColorWithMaxContrast(FromTransformInput()));
   ColorMixer mixer1(&mixer0);
   mixer1.AddSet({kColorSetTest1, {{kColorTest1, SK_ColorRED}}});
   EXPECT_EQ(SK_ColorGREEN,
@@ -207,9 +207,9 @@ TEST(ColorMixerTest, GetResultColorNoRecipe) {
 // initial value for its requested color.
 TEST(ColorMixerTest, GetResultColorNoSet) {
   ColorMixer mixer;
-  mixer[kColorTest0].AddTransform(FromColor(SK_ColorGREEN));
-  mixer[kColorTest1].AddTransform(
-      GetColorWithMaxContrast(FromTransformInput()));
+  mixer.AddRecipe(kColorTest0).AddTransform(FromColor(SK_ColorGREEN));
+  mixer.AddRecipe(kColorTest1)
+      .AddTransform(GetColorWithMaxContrast(FromTransformInput()));
   EXPECT_EQ(SK_ColorGREEN, mixer.GetResultColor(kColorTest0));
   EXPECT_NE(gfx::kPlaceholderColor, mixer.GetResultColor(kColorTest1));
 }
@@ -220,8 +220,8 @@ TEST(ColorMixerTest, GetResultColorIgnoresSet) {
   ColorMixer mixer;
   mixer.AddSet({kColorSetTest0,
                 {{kColorTest0, SK_ColorWHITE}, {kColorTest1, SK_ColorBLACK}}});
-  mixer[kColorTest0].AddTransform(FromColor(SK_ColorGREEN));
-  mixer[kColorTest1].AddTransform(FromColor(SK_ColorGREEN));
+  mixer.AddRecipe(kColorTest0).AddTransform(FromColor(SK_ColorGREEN));
+  mixer.AddRecipe(kColorTest1).AddTransform(FromColor(SK_ColorGREEN));
   EXPECT_EQ(SK_ColorGREEN, mixer.GetResultColor(kColorTest0));
   EXPECT_EQ(SK_ColorGREEN, mixer.GetResultColor(kColorTest1));
 }
@@ -231,12 +231,14 @@ TEST(ColorMixerTest, GetResultColorIgnoresSet) {
 TEST(ColorMixerTest, GetResultColorChained) {
   ColorMixer mixer;
   mixer.AddSet({kColorSetTest0, {{kColorTest1, SK_ColorWHITE}}});
-  mixer[kColorTest0].AddTransform(FromColor(gfx::kGoogleBlue050));
-  mixer[kColorTest1].AddTransform(BlendTowardMaxContrast(
-      GetColorWithMaxContrast(FromTransformInput()), 0x29));
-  mixer[kColorTest2].AddTransform(BlendForMinContrast(
-      FromColor(gfx::kGoogleBlue500), FromResultColor(kColorTest1),
-      FromResultColor(kColorTest0)));
+  mixer.AddRecipe(kColorTest0).AddTransform(FromColor(gfx::kGoogleBlue050));
+  mixer.AddRecipe(kColorTest1)
+      .AddTransform(BlendTowardMaxContrast(
+          GetColorWithMaxContrast(FromTransformInput()), 0x29));
+  mixer.AddRecipe(kColorTest2)
+      .AddTransform(BlendForMinContrast(FromColor(gfx::kGoogleBlue500),
+                                        FromResultColor(kColorTest1),
+                                        FromResultColor(kColorTest0)));
   EXPECT_EQ(SkColorSetRGB(0x89, 0xB3, 0xF8), mixer.GetResultColor(kColorTest2));
 }
 

ui/color/color_provider.cc

@@ -11,7 +11,7 @@
 
 namespace ui {
 
-ColorMixer& ColorProvider::AddMixer() {
+ColorMixer* ColorProvider::AddMixer() {
   // Adding a mixer could change any of the result colors.
   cache_.clear();
 
@@ -20,7 +20,7 @@ ColorMixer& ColorProvider::AddMixer() {
   // mixer for its result, and trust mixers to query each other back up the
   // chain as needed.
   mixers_.emplace_front(mixers_.empty() ? nullptr : &mixers_.front());
-  return mixers_.front();
+  return &mixers_.front();
 }
 
 SkColor ColorProvider::GetColor(ColorId id, ColorVariant variant) const {

ui/color/color_provider.h

@@ -30,9 +30,9 @@ class COMPONENT_EXPORT(COLOR) ColorProvider {
   ColorProvider& operator=(const ColorProvider&) = delete;
   ~ColorProvider();
 
-  // Adds a mixer to the end of the current color pipeline.  Returns a reference
+  // Adds a mixer to the end of the current color pipeline.  Returns a pointer
   // to the added mixer so callers can subsequently add sets and/or recipes.
-  ColorMixer& AddMixer();
+  ColorMixer* AddMixer();
 
   // Returns the result color for |id| by applying the effects of each mixer in
   // order.  Returns gfx::kPlaceholderColor if no mixer knows how to construct

ui/color/color_provider_unittest.cc

@@ -11,6 +11,14 @@
 namespace ui {
 namespace {
 
+// Tests that AddMixer() returns non-null pointers, implying addition was
+// successful.  (Other tests below will verify the mixers have an effect.)
+TEST(ColorProviderTest, AddMixer) {
+  ColorProvider provider;
+  EXPECT_NE(nullptr, provider.AddMixer());
+  EXPECT_NE(nullptr, provider.AddMixer());
+}
+
 // Tests that when there are no mixers, GetColor() returns a placeholder value.
 TEST(ColorProviderTest, GetColorNoMixers) {
   EXPECT_EQ(gfx::kPlaceholderColor, ColorProvider().GetColor(kColorTest0));
@@ -20,7 +28,7 @@ TEST(ColorProviderTest, GetColorNoMixers) {
 // possible.
 TEST(ColorProviderTest, SingleMixer) {
   ColorProvider provider;
-  provider.AddMixer().AddSet({kColorSetTest0, {{kColorTest0, SK_ColorGREEN}}});
+  provider.AddMixer()->AddSet({kColorSetTest0, {{kColorTest0, SK_ColorGREEN}}});
   EXPECT_EQ(SK_ColorGREEN, provider.GetColor(kColorTest0));
   EXPECT_EQ(gfx::kPlaceholderColor, provider.GetColor(kColorTest1));
 }
@@ -29,8 +37,8 @@ TEST(ColorProviderTest, SingleMixer) {
 // use of both.
 TEST(ColorProviderTest, NonOverlappingMixers) {
   ColorProvider provider;
-  provider.AddMixer().AddSet({kColorSetTest0, {{kColorTest0, SK_ColorGREEN}}});
-  provider.AddMixer().AddSet({kColorSetTest1, {{kColorTest1, SK_ColorRED}}});
+  provider.AddMixer()->AddSet({kColorSetTest0, {{kColorTest0, SK_ColorGREEN}}});
+  provider.AddMixer()->AddSet({kColorSetTest1, {{kColorTest1, SK_ColorRED}}});
   EXPECT_EQ(SK_ColorGREEN, provider.GetColor(kColorTest0));
   EXPECT_EQ(SK_ColorRED, provider.GetColor(kColorTest1));
 }
@@ -39,8 +47,8 @@ TEST(ColorProviderTest, NonOverlappingMixers) {
 // added takes priority.
 TEST(ColorProviderTest, OverlappingMixers) {
   ColorProvider provider;
-  provider.AddMixer().AddSet({kColorSetTest0, {{kColorTest0, SK_ColorGREEN}}});
-  provider.AddMixer().AddSet({kColorSetTest0, {{kColorTest0, SK_ColorRED}}});
+  provider.AddMixer()->AddSet({kColorSetTest0, {{kColorTest0, SK_ColorGREEN}}});
+  provider.AddMixer()->AddSet({kColorSetTest0, {{kColorTest0, SK_ColorRED}}});
   EXPECT_EQ(SK_ColorRED, provider.GetColor(kColorTest0));
 }
 
@@ -48,10 +56,10 @@ TEST(ColorProviderTest, OverlappingMixers) {
 // This attempts to verify that nothing is badly wrong with color caching.
 TEST(ColorProviderTest, Caching) {
   ColorProvider provider;
-  provider.AddMixer().AddSet({kColorSetTest0, {{kColorTest0, SK_ColorGREEN}}});
+  provider.AddMixer()->AddSet({kColorSetTest0, {{kColorTest0, SK_ColorGREEN}}});
   EXPECT_EQ(SK_ColorGREEN, provider.GetColor(kColorTest0));
   EXPECT_EQ(SK_ColorGREEN, provider.GetColor(kColorTest0));
-  provider.AddMixer().AddSet({kColorSetTest0, {{kColorTest0, SK_ColorRED}}});
+  provider.AddMixer()->AddSet({kColorSetTest0, {{kColorTest0, SK_ColorRED}}});
   EXPECT_EQ(SK_ColorRED, provider.GetColor(kColorTest0));
 }
 

ui/color/color_transform_unittest.cc

@@ -156,7 +156,7 @@ TEST(ColorTransformTest, FromResultColor) {
   ColorMixer mixer;
   mixer.AddSet({kColorSetTest0,
                 {{kColorTest0, SK_ColorGREEN}, {kColorTest1, kTest1Color}}});
-  mixer[kColorTest0].AddTransform(FromInputColor(kColorTest1));
+  mixer.AddRecipe(kColorTest0).AddTransform(FromInputColor(kColorTest1));
   const auto verify_color = [&](SkColor input) {
     EXPECT_EQ(kTest1Color, transform.Run(input, mixer));
   };