Consider inner WebContents when choosing whether to snapshot for offline pages

RecentTabHelper::WebContentsWasHidden has several conditions for saving
a snapshot. One of which is to not snapshot for custom tabs. We try to
determine if a WebContents is a custom tab, but for inner WebContents,
such as portals, we DCHECK as they are not directly associated with a
tab.

We now use the outermost WebContents to determine whether we are in a
custom tab.

Bug: 958825
Change-Id: Ia7e2ebe93e3a73741c5d0df467f20bc8bc9c38ba
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1635969Reviewed-by: Yaron Friedman <yfriedman@chromium.org>
Reviewed-by: Dmitry Titov <dimich@chromium.org>
Commit-Queue: Kevin McNee <mcnee@chromium.org>
Cr-Commit-Position: refs/heads/master@{#664746}

chrome/android/javatests/src/org/chromium/chrome/browser/portals/PortalsTest.java

@@ -130,4 +130,38 @@ public class PortalsTest {
         executeScriptAndAwaitSwap(tab, "activatePortal();");
         executeScriptAndAwaitSwap(tab, "reactivatePredecessor();");
     }
+
+    /**
+     * Tests that an adopted predecessor can be destroyed.
+     */
+    @Test
+    @MediumTest
+    @Feature({"Portals"})
+    public void testRemovePredecessor() throws Exception {
+        mActivityTestRule.startMainActivityWithURL(
+                mTestServer.getURL("/chrome/test/data/android/portals/predecessor-adoption.html"));
+
+        final Tab tab = mActivityTestRule.getActivity().getActivityTab();
+
+        executeScriptAndAwaitSwap(tab, "activatePortal();");
+        JavaScriptUtils.executeJavaScriptAndWaitForResult(
+                tab.getWebContents(), "removePredecessor();");
+    }
+
+    /**
+     * Tests that a previously activated portal can be destroyed.
+     */
+    @Test
+    @MediumTest
+    @Feature({"Portals"})
+    public void testRemovePreviouslyActivePortal() throws Exception {
+        mActivityTestRule.startMainActivityWithURL(
+                mTestServer.getURL("/chrome/test/data/android/portals/predecessor-adoption.html"));
+
+        final Tab tab = mActivityTestRule.getActivity().getActivityTab();
+
+        executeScriptAndAwaitSwap(tab, "activatePortal();");
+        executeScriptAndAwaitSwap(tab, "reactivatePredecessor();");
+        JavaScriptUtils.executeJavaScriptAndWaitForResult(tab.getWebContents(), "removePortal();");
+    }
 }

chrome/browser/offline_pages/recent_tab_helper.cc

@@ -312,12 +312,17 @@ void RecentTabHelper::WebContentsWasHidden() {
   // - A last_n snapshot is currently being saved.
   // - The tab is in the process of being closed.
   // - The tab is currently presented as a custom tab.
+  // Note that a WebContents may be embedded in another WebContents. The
+  // outermost WebContents is the one associated with the tab.
   if (!last_n_listen_to_tab_hidden_ || last_n_ongoing_snapshot_info_ ||
-      tab_is_closing_ || delegate_->IsCustomTab(web_contents())) {
+      tab_is_closing_ ||
+      delegate_->IsCustomTab(web_contents()->GetOutermostWebContents())) {
     DVLOG(1) << "Will not snapshot for last_n (reasons: "
              << !last_n_listen_to_tab_hidden_ << ", "
              << !!last_n_ongoing_snapshot_info_ << ", " << tab_is_closing_
-             << ", " << delegate_->IsCustomTab(web_contents())
+             << ", "
+             << delegate_->IsCustomTab(
+                    web_contents()->GetOutermostWebContents())
              << ") for: " << web_contents()->GetLastCommittedURL().spec();
     return;
   }