Android: Make TabFullscreenHandler Tab's UserData

This CL makes TabFullscreenHandler Tab's UserData so that Tab
doesn't have to manage |mFullscreenHandler|.

Bug: 924242
Change-Id: I5a3ea1fc15a8e5d09ab0b1a5ac048feaa2471a6d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1496272Reviewed-by: Ted Choc <tedchoc@chromium.org>
Reviewed-by: Jinsuk Kim <jinsukkim@chromium.org>
Commit-Queue: Jinsuk Kim <jinsukkim@chromium.org>
Cr-Commit-Position: refs/heads/master@{#638410}

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

@@ -289,8 +289,6 @@ public class Tab
     /** The current browser controls constraints. -1 if not set. */
     private @BrowserControlsState int mBrowserConstrolsConstraints = -1;
 
-    private final TabObserver mFullscreenHandler = new TabFullscreenHandler();
-
     private TabDelegateFactory mDelegateFactory;
 
     private BrowserControlsVisibilityDelegate mBrowserControlsVisibilityDelegate;
@@ -389,7 +387,7 @@ public class Tab
             }
         }
 
-        addObserver(mFullscreenHandler);
+        TabFullscreenHandler.createForTab(this);
 
         if (incognito) {
             CipherFactory.getInstance().triggerKeyGeneration();
@@ -1312,7 +1310,6 @@ public class Tab
     protected void didFinishPageLoad(String url) {
         mIsTabStateDirty = true;
         updateTitle();
-        updateFullscreenEnabledState();
 
         for (TabObserver observer : mObservers) observer.onPageLoadFinished(this, url);
         mIsBeingRestored = false;

chrome/android/java/src/org/chromium/chrome/browser/tab/TabFullscreenHandler.java

@@ -4,6 +4,8 @@
 
 package org.chromium.chrome.browser.tab;
 
+import org.chromium.base.UserData;
+import org.chromium.base.UserDataHost;
 import org.chromium.chrome.browser.fullscreen.FullscreenOptions;
 import org.chromium.content_public.browser.SelectionPopupController;
 import org.chromium.content_public.common.BrowserControlsState;
@@ -11,10 +13,32 @@ import org.chromium.content_public.common.BrowserControlsState;
 /**
  * {@link TabObserver} for basic fullscreen operations for {@link Tab}.
  */
-public final class TabFullscreenHandler extends EmptyTabObserver {
+public final class TabFullscreenHandler extends EmptyTabObserver implements UserData {
+    private static final Class<TabFullscreenHandler> USER_DATA_KEY = TabFullscreenHandler.class;
+
+    private final Tab mTab;
+
     /** A runnable to delay the enabling of fullscreen mode if necessary. */
     private Runnable mEnterFullscreenRunnable;
 
+    public static void createForTab(Tab tab) {
+        UserDataHost host = tab.getUserDataHost();
+        assert host.getUserData(USER_DATA_KEY) == null;
+        host.setUserData(USER_DATA_KEY, new TabFullscreenHandler(tab));
+    }
+
+    private TabFullscreenHandler(Tab tab) {
+        mTab = tab;
+        mTab.addObserver(this);
+    }
+
+    // UserData
+
+    @Override
+    public void destroy() {
+        mTab.removeObserver(this);
+    }
+
     @Override
     public void onSSLStateUpdated(Tab tab) {
         tab.updateFullscreenEnabledState();
@@ -81,4 +105,9 @@ public final class TabFullscreenHandler extends EmptyTabObserver {
             tab.updateBrowserControlsState(BrowserControlsState.SHOWN, false);
         }
     }
+
+    @Override
+    public void onPageLoadFinished(Tab tab, String url) {
+        tab.updateFullscreenEnabledState();
+    }
 }