[Android] Enable ApplicationStatus for WebView.

base/android/java/src/org/chromium/base/ApplicationStatus.java

Index: base/android/java/src/org/chromium/base/ApplicationStatus.java
diff --git a/base/android/java/src/org/chromium/base/ApplicationStatus.java b/base/android/java/src/org/chromium/base/ApplicationStatus.java
index 5035b9cabfb0f182d869d154ced60f290bdcccdc..c6ff033593e9cb875bda4d80960cfaa24c81e11f 100644
--- a/base/android/java/src/org/chromium/base/ApplicationStatus.java
+++ b/base/android/java/src/org/chromium/base/ApplicationStatus.java
@@ -64,6 +64,13 @@ public class ApplicationStatus {
     private static ApplicationStateListener sNativeApplicationStateListener;
 
     /**
+     * If true means we are running in 'webview' mode, see {@link #initializeForWebView} for
+     * more details.
+     */
+    private static boolean sWebViewMode = false;

[boliu, 2015/10/01 16:59:02]

+1 to a more contained name, instead of "isWebView". We generally avoid having
any code know explicitly it's running webview vs chrome, because the more things
will start depending on it, webview will diverge from chrome.

I'm bad at names, maybe ehh... IsApplicationBoundAfterOnCreate, or something
like that..?

[timvolodine, 2015/10/02 14:55:09]

went for sActivityLifecycleIndependentMode

+    private static Context sWrappedApplicationContext;

[boliu, 2015/10/01 16:59:02]

"Wrapped" is meaningless in base, so just sApplicationContext is fine. But do
leave a comment that only use this as context, instead of casting from
sApplication, since they may not always be the same object

[timvolodine, 2015/10/02 14:55:09]

Done.

+
+    /**
      * A map of which observers listen to state changes from which {@link Activity}.
      */
     private static final Map<Activity, ActivityInfo> sActivityInfo =
@@ -109,28 +116,13 @@ public class ApplicationStatus {
 
     /**
      * Initializes the activity status for a specified application.
+     * This method only registers for ActivityLifecycle changes.
      *
      * @param application The application whose status you wish to monitor.
      */
-    public static void initialize(BaseChromiumApplication application) {
+    private static void initializeLifecycleCallbacks(Application application) {
         sApplication = application;
 
-        application.registerWindowFocusChangedListener(
-                new BaseChromiumApplication.WindowFocusChangedListener() {
-                    @Override
-                    public void onWindowFocusChanged(Activity activity, boolean hasFocus) {
-                        if (!hasFocus || activity == sActivity) return;
-
-                        int state = getStateForActivity(activity);
-
-                        if (state != ActivityState.DESTROYED && state != ActivityState.STOPPED) {
-                            sActivity = activity;
-                        }
-
-                        // TODO(dtrainor): Notify of active activity change?
-                    }
-                });
-
         application.registerActivityLifecycleCallbacks(new ActivityLifecycleCallbacks() {
             @Override
             public void onActivityCreated(final Activity activity, Bundle savedInstanceState) {
@@ -168,6 +160,46 @@ public class ApplicationStatus {
     }
 
     /**
+     * Initializes the activity status for a specified application.
+     *
+     * @param application The application whose status you wish to monitor.
+     */
+    public static void initialize(BaseChromiumApplication application) {
+        initializeLifecycleCallbacks(application);
+
+        application.registerWindowFocusChangedListener(
+                new BaseChromiumApplication.WindowFocusChangedListener() {
+                    @Override
+                    public void onWindowFocusChanged(Activity activity, boolean hasFocus) {
+                        if (!hasFocus || activity == sActivity) return;
+
+                        int state = getStateForActivity(activity);
+
+                        if (state != ActivityState.DESTROYED && state != ActivityState.STOPPED) {
+                            sActivity = activity;
+                        }
+
+                        // TODO(dtrainor): Notify of active activity change?
+                    }
+                });
+    }
+
+    /**
+     * Initializes ApplicationStatus in WebView mode, which is different from the regular
+     * initialization (@see initialize) in the following ways:
+     *   1. We currently don't listen to focus changes (hence sActivity is always null).
+     *   2. getApplicationContext returns wrapped application context.
+     *   3. sActivityInfo does not have a particular update ordering because WebView can
+     *      be initialized at different times during activity lifecycle.
+     */
+    public static void initializeForWebView(Application application,
+            Context wrappedApplicationContext) {
+        sWebViewMode = true;
+        sWrappedApplicationContext = wrappedApplicationContext;
+        initializeLifecycleCallbacks(application);
+    }
+
+    /**
      * Must be called by the main activity when it changes state.
      *
      * @param activity Current activity.
@@ -176,18 +208,25 @@ public class ApplicationStatus {
     private static void onStateChange(Activity activity, int newState) {
         if (activity == null) throw new IllegalArgumentException("null activity is not supported");
 
-        if (sActivity == null
-                || newState == ActivityState.CREATED
-                || newState == ActivityState.RESUMED
-                || newState == ActivityState.STARTED) {
-            sActivity = activity;
-        }
-
         int oldApplicationState = getStateForApplication();
 
-        if (newState == ActivityState.CREATED) {
-            assert !sActivityInfo.containsKey(activity);
-            sActivityInfo.put(activity, new ActivityInfo());
+        if (sWebViewMode) {
+            assert sActivity == null;
+            if (!sActivityInfo.containsKey(activity)) {
+                sActivityInfo.put(activity, new ActivityInfo());
+            }
+        } else {
+            if (sActivity == null
+                    || newState == ActivityState.CREATED
+                    || newState == ActivityState.RESUMED
+                    || newState == ActivityState.STARTED) {
+                sActivity = activity;
+            }
+
+            if (newState == ActivityState.CREATED) {
+                assert !sActivityInfo.containsKey(activity);
+                sActivityInfo.put(activity, new ActivityInfo());
+            }
         }
 
         // Invalidate the cached application state.
@@ -233,8 +272,11 @@ public class ApplicationStatus {
     /**
      * @return The most recent focused {@link Activity} tracked by this class.  Being focused means
      *         out of all the activities tracked here, it has most recently gained window focus.
+     *         Note that in 'webview mode' the returned Activity is currently always null
+     *         (see crbug.com/538175).
      */
     public static Activity getLastTrackedFocusedActivity() {
+        assert !sWebViewMode || sActivity == null;  // sWebViewMode implies sActivity == null
         return sActivity;
     }
 
@@ -253,7 +295,8 @@ public class ApplicationStatus {
      * @return The {@link Context} for the {@link Application}.
      */
     public static Context getApplicationContext() {
-        return sApplication != null ? sApplication.getApplicationContext() : null;
+        if (sApplication == null) return null;
+        return sWebViewMode ? sWrappedApplicationContext : sApplication.getApplicationContext();

[boliu, 2015/10/01 16:59:02]

See, webview mode is already creeping in.

Chrome should just set sApplicationContext to to
sApplication.getApplicationContext in init. Then can just return
sApplicationContext here.

[timvolodine, 2015/10/02 14:55:09]

right, done.

     }
 
     /**