[ChromeColors] Revert theme changes when user navigates away from webUI

This CL calls ChromeColorsService::RevertThemeChanges() from
~ChromeCustomizeThemesHandler() to not apply unconfirmed changes when
the user navigates away from a webUI page with the color picker.

Screencast: https://drive.google.com/file/d/1APJjUVJv3WL3m2Nr71ukAG9o1ZRMnMMc/view?usp=sharing

Bug: 1095530, 1115301
Change-Id: Ic2a7a886b1e9ad8328687621a5dd9e44d1563280
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2414175
Commit-Queue: Alex Ilin <alexilin@chromium.org>
Reviewed-by: Tibor Goldschwendt <tiborg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#807893}

chrome/browser/ui/webui/customize_themes/chrome_customize_themes_handler.cc

@@ -43,7 +43,10 @@ ChromeCustomizeThemesHandler::ChromeCustomizeThemesHandler(
                               content::NotificationService::AllSources());
 }
 
-ChromeCustomizeThemesHandler::~ChromeCustomizeThemesHandler() = default;
+ChromeCustomizeThemesHandler::~ChromeCustomizeThemesHandler() {
+  // Revert any unconfirmed theme changes.
+  chrome_colors_service_->RevertThemeChangesForTab(web_contents_);
+}
 
 void ChromeCustomizeThemesHandler::ApplyAutogeneratedTheme(
     const SkColor& frame_color) {

chrome/browser/ui/webui/customize_themes/chrome_customize_themes_handler_unittest.cc

@@ -142,6 +142,15 @@ class ChromeCustomizeThemesHandlerTest : public testing::Test {
         web_contents_, profile());
   }
 
+  void TearDown() override {
+    if (handler_) {
+      // Confirm all pending changes to not trigger a revert on destruction.
+      handler_->ConfirmThemeChanges();
+    }
+  }
+
+  void ResetHandler() { handler_.reset(); }
+
   extensions::TestExtensionEnvironment* env() {
     return &extension_environment_;
   }
@@ -272,3 +281,19 @@ TEST_F(ChromeCustomizeThemesHandlerTest, ConfirmThemeChanges) {
   handler()->RevertThemeChanges();
   EXPECT_TRUE(theme_service()->UsingDefaultTheme());
 }
+
+TEST_F(ChromeCustomizeThemesHandlerTest, ResetHandler) {
+  constexpr SkColor kAutogeneratedThemeColor = SK_ColorBLUE;
+  theme_service()->BuildAutogeneratedThemeFromColor(kAutogeneratedThemeColor);
+
+  handler()->ApplyDefaultTheme();
+  EXPECT_TRUE(theme_service()->UsingDefaultTheme());
+  // Cleans all pending SetTheme() calls.
+  base::RunLoop().RunUntilIdle();
+
+  // Handler should revert theme changes when it's destructed.
+  ResetHandler();
+  EXPECT_TRUE(theme_service()->UsingAutogeneratedTheme());
+  EXPECT_EQ(kAutogeneratedThemeColor,
+            theme_service()->GetAutogeneratedThemeColor());
+}

ui/webui/resources/cr_components/customize_themes/customize_themes.js

@@ -78,8 +78,9 @@ export class CustomizeThemesElement extends mixinBehaviors
 
   /** @override */
   disconnectedCallback() {
-    super.disconnectedCallback();
+    this.revertThemeChanges();
     this.callbackRouter_.removeListener(assert(this.setThemeListenerId_));
+    super.disconnectedCallback();
   }
 
   confirmThemeChanges() {