[CSC] Add signin flow test

1. If already signed in, skip the sign-in flow.
2. Also added an sync enum for the companion access point.

(cherry picked from commit 4ca4170)

Bug: b/280536741, crbug.com/1449021
Change-Id: I6eccdceab94c839925e3bc85a882f8c3846c6b82
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4546596
Commit-Queue: Shakti Sahu <shaktisahu@chromium.org>
Reviewed-by: Michael Crouse <mcrouse@chromium.org>
Cr-Original-Commit-Position: refs/heads/main@{#1148182}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4582687
Cr-Commit-Position: refs/branch-heads/5790@{#235}
Cr-Branched-From: 1d71a33-refs/heads/main@{#1148114}

chrome/browser/ui/views/side_panel/search_companion/companion_page_browsertest.cc

@@ -12,6 +12,7 @@
 #include "base/test/bind.h"
 #include "base/test/metrics/histogram_tester.h"
 #include "base/test/scoped_feature_list.h"
+#include "build/buildflag.h"
 #include "chrome/browser/companion/core/companion_metrics_logger.h"
 #include "chrome/browser/companion/core/constants.h"
 #include "chrome/browser/companion/core/features.h"
@@ -749,6 +750,37 @@ IN_PROC_BROWSER_TEST_F(CompanionPageBrowserTest, ExpsPromoURLLoadsInNewTab) {
       kExpectedExpsPromoUrl));
 }
 
+#if !BUILDFLAG(IS_CHROMEOS_ASH) && !BUILDFLAG(IS_CHROMEOS_LACROS)
+IN_PROC_BROWSER_TEST_F(CompanionPageBrowserTest, SigninLoadsInNewTab) {
+  ukm::TestAutoSetUkmRecorder ukm_recorder;
+  // Load a page on the active tab.
+  ASSERT_TRUE(
+      ui_test_utils::NavigateToURL(browser(), CreateUrl(kHost, kRelativeUrl1)));
+  ASSERT_EQ(side_panel_coordinator()->GetCurrentEntryId(), absl::nullopt);
+
+  EXPECT_EQ(1, browser()->tab_strip_model()->count());
+
+  // Open companion companion via toolbar entry point.
+  side_panel_coordinator()->Show(SidePanelEntry::Id::kSearchCompanion);
+  EXPECT_TRUE(side_panel_coordinator()->IsSidePanelShowing());
+
+  WaitForCompanionToBeLoaded();
+  EXPECT_EQ(side_panel_coordinator()->GetCurrentEntryId(),
+            SidePanelEntry::Id::kSearchCompanion);
+
+  // Show sign-in promo, user accepts it.
+  CompanionScriptBuilder builder(MethodType::kOnPromoAction);
+  builder.promo_type = PromoType::kSignin;
+  builder.promo_action = PromoAction::kAccepted;
+  EXPECT_TRUE(ExecJs(builder.Build()));
+
+  // Verify that a new tab opens up to load the sign-in URL.
+  WaitForTabCount(2);
+  EXPECT_TRUE(web_contents()->GetVisibleURL().spec().starts_with(
+      "https://accounts.google.com/signin/chrome/sync"));
+}
+#endif
+
 IN_PROC_BROWSER_TEST_F(CompanionPageBrowserTest, RegionSearchClick) {
   ukm::TestAutoSetUkmRecorder ukm_recorder;
 

chrome/browser/ui/webui/side_panel/companion/signin_delegate_impl.cc

@@ -46,6 +46,10 @@ bool SigninDelegateImpl::IsSignedIn() {
 }
 
 void SigninDelegateImpl::StartSigninFlow() {
+  if (IsSignedIn()) {
+    return;
+  }
+
   DCHECK(AllowedSignin());
 
   // Show the promo here.