Move setCoveredByChild methods to Tab.

Moves a subclass Tab method up to superclass to eliminate the dependency
on the downstream Tab implementation. Removes the no longer necessary
method from TabDelegate.

BUG=464934

Review URL: https://codereview.chromium.org/988323005

Cr-Commit-Position: refs/heads/master@{#319737}

chrome/android/java/src/org/chromium/chrome/browser/Tab.java

@@ -2603,6 +2603,23 @@ public class Tab implements ViewGroup.OnHierarchyChangeListener,
         return nativeHasPrerenderedUrl(mNativeTabAndroid, url);
     }
 
+    /**
+     * Check if the tab is covered by its child activity.
+     * @return Whether the tab is covered by its child activity.
+     */
+    public boolean isCoveredByChildActivity() {
+        // Default return value, this is only used by subclasses.
+        return false;
+    }
+
+    /**
+     * Update whether the tab is covered by its child activity.
+     * @param isCoveredByChildActivity Whether the tab is covered by its child activity.
+     */
+    public void setCoveredByChildActivity(boolean isCoveredByChildActivity) {
+        // Empty implementation, only used by subclasses.
+    }
+
     /**
      * Ensures the counter is at least as high as the specified value.  The counter should always
      * point to an unused ID (which will be handed out next time a request comes in).  Exposed so

chrome/android/java/src/org/chromium/chrome/browser/tabmodel/document/DocumentTabModelImpl.java

@@ -439,7 +439,7 @@ public class DocumentTabModelImpl extends TabModelJniBridge implements DocumentT
         Entry currentEntry = mEntryMap.get(id);
         String currentUrl = tab.getUrl();
         boolean canGoBack = tab.canGoBack();
-        boolean isCoveredByChildActivity = mTabDelegate.isTabCoveredByChildActivity(tab);
+        boolean isCoveredByChildActivity = tab.isCoveredByChildActivity();
         TabState state = tab.getState();
         if (currentEntry != null
                 && currentEntry.tabId == id

chrome/android/java/src/org/chromium/chrome/browser/tabmodel/document/TabDelegate.java

@@ -53,11 +53,4 @@ public interface TabDelegate {
      * @param url URL to spawn a Tab for.
      */
     void createTabForDevTools(String url);
-
-    /**
-     * Check if the tab is covered by its child activity.
-     * @param tab Tab to be checked.
-     * @return Whether the tab is covered by its child activity.
-     */
-    boolean isTabCoveredByChildActivity(Tab tab);
 }
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chrome/test/android/javatests/src/org/chromium/chrome/test/util/browser/tabmodel/document/MockTabDelegate.java

@@ -41,9 +41,4 @@ public class MockTabDelegate implements TabDelegate {
     @Override
     public void createTabForDevTools(String url) {
     }
-
-    @Override
-    public boolean isTabCoveredByChildActivity(Tab tab) {
-        return false;
-    }
 }
\ No newline at end of file