Fixes #430 - Hides software keyboard when you background the app

app/src/main/java/org/mozilla/fenix/HomeActivity.kt

@@ -4,10 +4,12 @@
 
 package org.mozilla.fenix
 
+import android.app.Activity
 import android.content.Context
 import android.os.Bundle
 import android.util.AttributeSet
 import android.view.View
+import android.view.inputmethod.InputMethodManager
 import androidx.appcompat.app.AppCompatActivity
 import androidx.appcompat.widget.Toolbar
 import androidx.navigation.fragment.NavHostFragment
@@ -67,6 +69,19 @@ open class HomeActivity : AppCompatActivity() {
         super.onBackPressed()
     }
 
+    override fun onPause() {
+        super.onPause()
+        hideSoftwareKeyboard()
+    }
+
+    private fun hideSoftwareKeyboard() {
+        (getSystemService(Activity.INPUT_METHOD_SERVICE) as InputMethodManager).apply {
+            currentFocus?.also {
+                this.hideSoftInputFromWindow(it.windowToken, 0)
+            }
+        }
+    }
+
     private fun openToBrowser() {
         val sessionId = SafeIntent(intent).getStringExtra(IntentProcessor.ACTIVE_SESSION_ID)
         val host = supportFragmentManager.findFragmentById(R.id.container) as NavHostFragment