Fix some thread handling issues in InputMethodManager

- Make sure onCheckIsTextEditor should be called on the UI thread for
preventing exception in some cases that will break start input background
thread.

- Refine IMM#checkFocus and DelegateImpl#startInput to be out of
lock object to prevent start input background thread may blocked by other
methods which already inside the lock.

- Cache InputMethodManagerDelegate object for ImeFocusController#getDelegate.

Fix: 147447217
Bug: 141738570
Test: manual as test steps:
     1) Launch Keeeps app, type some web-URL link.
     2) Long press on any URL link > From the toolbar select "open / browser"
        and observe.
     3) Expect the soft-keyboard should be hidden after entering the
     browser page.
Test: atest CtsInputMethodTestCases

Change-Id: I098df41f935438bf1889fb030c7a3e7a0645a168

core/java/android/view/ImeFocusController.java

@@ -38,6 +38,7 @@ public final class ImeFocusController {
     private boolean mHasImeFocus = false;
     private View mServedView;
     private View mNextServedView;
+    private InputMethodManagerDelegate mDelegate;
 
     @UiThread
     ImeFocusController(@NonNull ViewRootImpl viewRootImpl) {
@@ -45,7 +46,11 @@ public final class ImeFocusController {
     }
 
     private InputMethodManagerDelegate getImmDelegate() {
-        return mViewRootImpl.mContext.getSystemService(InputMethodManager.class).getDelegate();
+        if (mDelegate == null) {
+            mDelegate = mViewRootImpl.mContext.getSystemService(
+                    InputMethodManager.class).getDelegate();
+        }
+        return mDelegate;
     }
 
     @UiThread

core/java/android/view/inputmethod/InputMethodManager.java

@@ -59,12 +59,12 @@ import android.util.PrintWriterPrinter;
 import android.util.Printer;
 import android.util.SparseArray;
 import android.view.Display;
+import android.view.ImeFocusController;
 import android.view.ImeInsetsSourceConsumer;
 import android.view.InputChannel;
 import android.view.InputEvent;
 import android.view.InputEventSender;
 import android.view.KeyEvent;
-import android.view.ImeFocusController;
 import android.view.View;
 import android.view.ViewRootImpl;
 import android.view.WindowManager.LayoutParams.SoftInputModeFlags;
@@ -562,14 +562,23 @@ public final class InputMethodManager {
         public boolean startInput(@StartInputReason int startInputReason, View focusedView,
                 @StartInputFlags int startInputFlags, @SoftInputModeFlags int softInputMode,
                 int windowFlags) {
+            final View servedView;
             synchronized (mH) {
                 mCurrentTextBoxAttribute = null;
                 mCompletions = null;
                 mServedConnecting = true;
-                if (getServedViewLocked() != null && !getServedViewLocked().onCheckIsTextEditor()) {
-                    // servedView has changed and it's not editable.
-                    maybeCallServedViewChangedLocked(null);
-                }
+                servedView = getServedViewLocked();
+            }
+            if (servedView != null && servedView.getHandler() != null) {
+                // Make sure View checks should be on the UI thread.
+                servedView.getHandler().post(() -> {
+                    if (!servedView.onCheckIsTextEditor()) {
+                        // servedView has changed and it's not editable.
+                        synchronized (mH) {
+                            maybeCallServedViewChangedLocked(null);
+                        }
+                    }
+                });
             }
             return startInputInner(startInputReason,
                     focusedView != null ? focusedView.getWindowToken() : null, startInputFlags,
@@ -607,21 +616,22 @@ public final class InputMethodManager {
                 mWindowFocusGainFuture.cancel(false /* mayInterruptIfRunning */);
             }
             mWindowFocusGainFuture = mStartInputWorker.submit(() -> {
-                synchronized (mH) {
-                    if (mCurRootView == null) {
+                final ImeFocusController controller = getFocusController();
+                if (controller == null) {
+                    return;
+                }
+                if (controller.checkFocus(forceNewFocus1, false)) {
+                    // We need to restart input on the current focus view.  This
+                    // should be done in conjunction with telling the system service
+                    // about the window gaining focus, to help make the transition
+                    // smooth.
+                    if (startInput(StartInputReason.WINDOW_FOCUS_GAIN,
+                            focusedView, startInputFlags, softInputMode, windowFlags)) {
                         return;
                     }
-                    if (mCurRootView.getImeFocusController().checkFocus(forceNewFocus1, false)) {
-                        // We need to restart input on the current focus view.  This
-                        // should be done in conjunction with telling the system service
-                        // about the window gaining focus, to help make the transition
-                        // smooth.
-                        if (startInput(StartInputReason.WINDOW_FOCUS_GAIN,
-                                focusedView, startInputFlags, softInputMode, windowFlags)) {
-                            return;
-                        }
-                    }
+                }
 
+                synchronized (mH) {
                     // For some reason we didn't do a startInput + windowFocusGain, so
                     // we'll just do a window focus gain and call it a day.
                     try {
@@ -716,6 +726,15 @@ public final class InputMethodManager {
         }
     }
 
+    private ImeFocusController getFocusController() {
+        synchronized (mH) {
+            if (mCurRootView != null) {
+                return mCurRootView.getImeFocusController();
+            }
+            return null;
+        }
+    }
+
     /**
      * Returns {@code true} when the given view has been served by Input Method.
      */
@@ -1793,6 +1812,12 @@ public final class InputMethodManager {
         startInputInner(StartInputReason.APP_CALLED_RESTART_INPUT_API, null, 0, 0, 0);
     }
 
+    /**
+     * Called when {@link DelegateImpl#startInput}, {@link #restartInput(View)},
+     * {@link #MSG_BIND} or {@link #MSG_UNBIND}.
+     * Note that this method should *NOT* be called inside of {@code mH} lock to prevent start input
+     * background thread may blocked by other methods which already inside {@code mH} lock.
+     */
     boolean startInputInner(@StartInputReason int startInputReason,
             @Nullable IBinder windowGainingFocus, @StartInputFlags int startInputFlags,
             @SoftInputModeFlags int softInputMode, int windowFlags) {
@@ -1976,15 +2001,16 @@ public final class InputMethodManager {
     }
 
     /**
+     * Check the next served view from {@link ImeFocusController} if needs to start input.
+     * Note that this method should *NOT* be called inside of {@code mH} lock to prevent start input
+     * background thread may blocked by other methods which already inside {@code mH} lock.
      * @hide
      */
     @UnsupportedAppUsage
     public void checkFocus() {
-        synchronized (mH) {
-            if (mCurRootView != null) {
-                mCurRootView.getImeFocusController().checkFocus(false /* forceNewFocus */,
-                        true /* startInput */);
-            }
+        final ImeFocusController controller = getFocusController();
+        if (controller != null) {
+            controller.checkFocus(false /* forceNewFocus */, true /* startInput */);
         }
     }