Change fragment's onCreateView() and onStart() to make it resumable

Fragment is detached from the activity when user says "OKG, set a timer for 1 minute", or use swipe from edge to "close" the player. When it is attached back to activity by clicking on home view's tile, onCreateView() and onStart() will be called again, but cast views and CastWebContentsSurfaceHelper already attached with current WebContents should be reused.

Change-Id: Ibc6dc3a31cd0ff3fc31e16c879537db43185b2f4

Bug: b/72838507

Test: 1. Say "OKG, play a video" and see cast fragment shown; 2. Say "OKG, set a timer for 1 minute" and dismiss the timer page, see cast fragment recovered correctly and video could be resume; 3. Check log output and see 2nd call of onCreateView() and onStart() won't recreate new fragment view and reset webconent.

TODO(vincentli): Add a test case to cover CastWebContentsFragment's lifecycle

Change-Id: Ibc6dc3a31cd0ff3fc31e16c879537db43185b2f4
Reviewed-on: https://chromium-review.googlesource.com/898602
Commit-Queue: Zhiheng(Vincent) Li <vincentli@google.com>
Reviewed-by: Stephen Lanham <slan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#534131}

chromecast/browser/android/apk/src/org/chromium/chromecast/shell/CastWebContentsFragment.java

@@ -26,6 +26,8 @@ import org.chromium.content_public.browser.WebContents;
  * CastWebContentsFragment should be removed from the activity holding it.
  * Similarily, if the fragment is removed from a activity or the activity holding
  * it is destroyed, CastContentWindowAndroid should be notified by intent.
+ *
+ * TODO(vincentli): Add a test case to test its lifecycle
  */
 public class CastWebContentsFragment extends Fragment {
     private static final String TAG = "cr_CastWebContentFrg";
@@ -34,6 +36,8 @@ public class CastWebContentsFragment extends Fragment {
 
     private CastWebContentsSurfaceHelper mSurfaceHelper;
 
+    private View mFragmentRootView;
+
     @Override
     public void onCreate(Bundle savedInstanceState) {
         Log.d(TAG, "onCreate");
@@ -52,11 +56,14 @@ public class CastWebContentsFragment extends Fragment {
                     .show();
             return null;
         }
-
-        return inflater.cloneInContext(getContext())
+        if (mFragmentRootView == null) {
+            mFragmentRootView = inflater.cloneInContext(getContext())
                 .inflate(R.layout.cast_web_contents_activity, null);
+        }
+        return mFragmentRootView;
     }
 
+
     @Override
     public Context getContext() {
         if (mPackageContext == null) {
@@ -69,11 +76,12 @@ public class CastWebContentsFragment extends Fragment {
     public void onStart() {
         Log.d(TAG, "onStart");
         super.onStart();
-        if (mSurfaceHelper == null) {
-            mSurfaceHelper = new CastWebContentsSurfaceHelper(getActivity(), /* hostActivity */
+        if (mSurfaceHelper != null) {
+            return;
+        }
+        mSurfaceHelper = new CastWebContentsSurfaceHelper(getActivity(), /* hostActivity */
                     (FrameLayout) getView().findViewById(R.id.web_contents_container),
                     true /* showInFragment */);
-        }
         Bundle bundle = getArguments();
         bundle.setClassLoader(WebContents.class.getClassLoader());
         String uriString = bundle.getString(CastWebContentsComponent.INTENT_EXTRA_URI);
@@ -93,7 +101,6 @@ public class CastWebContentsFragment extends Fragment {
     public void onPause() {
         Log.d(TAG, "onPause");
         super.onPause();
-
         if (mSurfaceHelper != null) {
             mSurfaceHelper.onPause();
         }