[Safety Tips] Don't go to NTP when Safety Tip shown in CCT.

The New Tab Page in CCTs doesn't work quite like you'd expect (since
they don't happen in organically), so this CL prevents using the NTP
as the default "safe page" for Safety Tips when a better
recommendation isn't available.

Instead, this CL either navigates back (if possible), or closes the CCT
(if not possible). This isn't an ideal solution either, but there
probably isn't a magical option.

Bug: 1007029
Change-Id: I63f53e361d734f4b26480467f74b182612dd210b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2334591
Commit-Queue: Joe DeBlasio <jdeblasio@chromium.org>
Reviewed-by: Mustafa Emre Acer <meacer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#794672}

chrome/browser/reputation/safety_tip_infobar_delegate.cc

@@ -74,7 +74,7 @@ bool SafetyTipInfoBarDelegate::Accept() {
   action_taken_ = SafetyTipInteraction::kLeaveSite;
   auto url = safety_tip_status_ == security_state::SafetyTipStatus::kLookalike
                  ? suggested_url_
-                 : GURL(kSafetyTipLeaveSiteUrl);
+                 : GURL();
   LeaveSiteFromSafetyTip(web_contents_, url);
   return true;
 }

chrome/browser/reputation/safety_tip_ui_helper.cc

@@ -14,8 +14,20 @@
 #include "content/public/browser/web_contents.h"
 #include "ui/base/l10n/l10n_util.h"
 
+#if defined(OS_ANDROID)
+#include "chrome/browser/android/tab_android.h"
+#include "chrome/browser/ui/android/tab_model/tab_model.h"
+#include "chrome/browser/ui/android/tab_model/tab_model_list.h"
+#include "content/public/browser/navigation_controller.h"
+#endif
+
+namespace {
+
+// URL that the "leave site" button aborts to by default.
 const char kSafetyTipLeaveSiteUrl[] = "chrome://newtab";
 
+}  // namespace
+
 void RecordSafetyTipInteractionHistogram(content::WebContents* web_contents,
                                          SafetyTipInteraction interaction) {
   SecurityStateTabHelper* helper =
@@ -32,8 +44,32 @@ void LeaveSiteFromSafetyTip(content::WebContents* web_contents,
                             const GURL& safe_url) {
   RecordSafetyTipInteractionHistogram(web_contents,
                                       SafetyTipInteraction::kLeaveSite);
+  auto navigated_to = safe_url;
+  if (navigated_to.is_empty()) {
+    navigated_to = GURL(kSafetyTipLeaveSiteUrl);
+
+#if defined(OS_ANDROID)
+    if (TabAndroid::FromWebContents(web_contents)->IsCustomTab()) {
+      auto& controller = web_contents->GetController();
+      // For CCTs, just go back if we can...
+      if (controller.CanGoBack()) {
+        controller.GoBack();
+        return;
+      }
+      // ... or close the CCT otherwise.
+      auto* tab_model = TabModelList::GetTabModelForWebContents(web_contents);
+      if (tab_model) {
+        tab_model->CloseTabAt(tab_model->GetActiveIndex());
+        return;
+      }
+      // (And if we don't have a tab model for some reason, just navigate away
+      //  someplace at least slightly. To my knowledge, this shouldn't happen.)
+    }
+#endif
+  }
+
   content::OpenURLParams params(
-      safe_url, content::Referrer(), WindowOpenDisposition::CURRENT_TAB,
+      navigated_to, content::Referrer(), WindowOpenDisposition::CURRENT_TAB,
       ui::PAGE_TRANSITION_AUTO_TOPLEVEL, false /* is_renderer_initiated */);
   params.should_replace_current_entry = true;
   web_contents->OpenURL(params);

chrome/browser/reputation/safety_tip_ui_helper.h

@@ -14,16 +14,14 @@ namespace content {
 class WebContents;
 }
 
-// URL that the "leave site" button aborts to by default.
-extern const char kSafetyTipLeaveSiteUrl[];
-
 // Records a histogram for a user's interaction with a Safety Tip in the given
 // |web_contents|.
 void RecordSafetyTipInteractionHistogram(content::WebContents* web_contents,
                                          SafetyTipInteraction interaction);
 
 // Invokes action when 'leave site' button is clicked, and records a histogram.
-// Navigates to a safe URL, replacing the current page in the process.
+// Navigates to either |safe_url| (when !is_empty()), or a safe default
+// otherwise, replacing the current page in the process.
 void LeaveSiteFromSafetyTip(content::WebContents* web_contents,
                             const GURL& safe_url);
 

chrome/browser/ui/views/page_info/safety_tip_page_info_bubble_view.cc

@@ -251,7 +251,7 @@ void SafetyTipPageInfoBubbleView::ButtonPressed(views::Button* button,
       web_contents(),
       safety_tip_status_ == security_state::SafetyTipStatus::kLookalike
           ? suggested_url_
-          : GURL(kSafetyTipLeaveSiteUrl));
+          : GURL());
 }
 
 void SafetyTipPageInfoBubbleView::StyledLabelLinkClicked(