Bug 1404111 - Part 1 - Work around potential InputMethodManager bug when gaining focus. r=snorp

MozReview-Commit-ID: 2YnsMCZYckA

--HG--
extra : rebase_source : f4ae504a935b02dd39e4a154afdef41765a4db44

mobile/android/geckoview/src/main/java/org/mozilla/gecko/GeckoView.java

@@ -28,6 +28,7 @@ import android.content.Context;
 import android.content.SharedPreferences;
 import android.content.res.Resources;
 import android.database.Cursor;
+import android.graphics.Rect;
 import android.net.Uri;
 import android.os.Binder;
 import android.os.Bundle;
@@ -43,6 +44,7 @@ import android.view.KeyEvent;
 import android.view.View;
 import android.view.inputmethod.EditorInfo;
 import android.view.inputmethod.InputConnection;
+import android.view.inputmethod.InputMethodManager;
 
 public class GeckoView extends LayerView {
 
@@ -309,6 +311,7 @@ public class GeckoView extends LayerView {
 
     private PromptDelegate mPromptDelegate;
     private InputConnectionListener mInputConnectionListener;
+    private boolean mIsResettingFocus;
 
     private GeckoViewSettings mSettings;
 
@@ -706,6 +709,45 @@ public class GeckoView extends LayerView {
         return mSettings;
     }
 
+    @Override
+    public void onFocusChanged(boolean gainFocus, int direction, Rect previouslyFocusedRect) {
+        super.onFocusChanged(gainFocus, direction, previouslyFocusedRect);
+
+        if (gainFocus && !mIsResettingFocus) {
+            ThreadUtils.postToUiThread(new Runnable() {
+                @Override
+                public void run() {
+                    if (!isFocused()) {
+                        return;
+                    }
+
+                    final InputMethodManager imm = InputMethods.getInputMethodManager(getContext());
+                    // Bug 1404111:
+                    // Through View#onFocusChanged, the InputMethodManager queues up a checkFocus
+                    // call for the next spin of the message loop, so by posting this Runnable after
+                    // super#onFocusChanged, the IMM should have completed its focus change handling
+                    // at this point and we should be the active view for input handling.
+
+                    // If however onViewDetachedFromWindow for the previously active view gets
+                    // called *after* onFocusChanged, but *before* the focus change has been fully
+                    // processed by the IMM with the help of checkFocus, the IMM will lose track of
+                    // the currently active view, which means that we can't interact with the IME.
+                    if (!imm.isActive(GeckoView.this)) {
+                        // If that happens, we bring the IMM's internal state back into sync by
+                        // clearing and resetting our focus.
+                        mIsResettingFocus = true;
+                        clearFocus();
+                        // After calling clearFocus we might regain focus automatically, but we
+                        // explicitly request it again in case this doesn't happen.
+                        // If we've already got the focus back, this will then be a no-op anyway.
+                        requestFocus();
+                        mIsResettingFocus = false;
+                    }
+                }
+            });
+        }
+    }
+
     @Override
     public Handler getHandler() {
         if (mInputConnectionListener != null) {