Move duplicate code for exiting fullscreen to ChromeActivity

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

Index: chrome/android/java/src/org/chromium/chrome/browser/ChromeActivity.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/ChromeActivity.java b/chrome/android/java/src/org/chromium/chrome/browser/ChromeActivity.java
index 86464d8226568fb9a4eda2c99d3a0d236ae4e133..e9dddfb35b11e8385aa218e3aa251a7448f38498 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/ChromeActivity.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/ChromeActivity.java
@@ -122,6 +122,7 @@ import org.chromium.chrome.browser.webapps.AddToHomescreenDialog;
 import org.chromium.chrome.browser.widget.ControlContainer;
 import org.chromium.content.browser.ContentReadbackHandler;
 import org.chromium.content.browser.ContentReadbackHandler.GetBitmapCallback;
+import org.chromium.content.browser.ContentVideoView;
 import org.chromium.content.browser.ContentViewCore;
 import org.chromium.content.common.ContentSwitches;
 import org.chromium.content_public.browser.LoadUrlParams;
@@ -1210,6 +1211,23 @@ public abstract class ChromeActivity extends AsyncInitializationActivity
     }
 
     /**
+     * Exits the fullscreen mode, if any. Does nothing if no fullscreen is present.
+     * @return Whether the fullscreen mode is currently showing.
+     */
+    protected boolean exitFullscreenIfShowing() {
+        ContentVideoView view = ContentVideoView.getContentVideoView();
+        if (view != null && view.getContext() == this) {
+            view.exitFullscreen(false);
+            return true;
+        }
+        if (getFullscreenManager().getPersistentFullscreenMode()) {
+            getFullscreenManager().setPersistentFullscreenMode(false);
+            return true;
+        }
+        return false;
+    }
+
+    /**
      * Initializes the {@link CompositorViewHolder} with the relevant content it needs to properly
      * show content on the screen.
      * @param layoutManager             A {@link LayoutManagerDocument} instance.  This class is