[Android] Fix spellcheck JNI crash when a tab is closed.

components/spellcheck/browser/spellcheck_message_filter_platform_android.cc

Index: components/spellcheck/browser/spellcheck_message_filter_platform_android.cc
diff --git a/components/spellcheck/browser/spellcheck_message_filter_platform_android.cc b/components/spellcheck/browser/spellcheck_message_filter_platform_android.cc
index 50a0e5a2d9b7b750ba7639e915a6a7847687b18c..ed3c41e3c8d006a0f0595f09b9a45cba73fbeb51 100644
--- a/components/spellcheck/browser/spellcheck_message_filter_platform_android.cc
+++ b/components/spellcheck/browser/spellcheck_message_filter_platform_android.cc
@@ -19,8 +19,14 @@ SpellCheckMessageFilterPlatform::SpellCheckMessageFilterPlatform(
 
 void SpellCheckMessageFilterPlatform::OverrideThreadForMessage(
     const IPC::Message& message, BrowserThread::ID* thread) {
-  if (message.type() == SpellCheckHostMsg_RequestTextCheck::ID)
-    *thread = BrowserThread::UI;
+  switch (message.type()) {
+    case SpellCheckHostMsg_RequestTextCheck::ID:
+    case SpellCheckHostMsg_ToggleSpellCheck::ID:
+      *thread = BrowserThread::UI;
+      break;
+    default:
+      break;
+  }
 }
 
 bool SpellCheckMessageFilterPlatform::OnMessageReceived(
@@ -91,3 +97,9 @@ void SpellCheckMessageFilterPlatform::OnToggleSpellCheck(
   if (!enabled)
     impl_->DisconnectSession();
 }
+
+void SpellCheckMessageFilterPlatform::OnDestruct() const {
+  // Needs to be destroyed on the UI thread, to avoid race conditions
+  // on the java side during clean-up.
+  BrowserThread::DeleteOnUIThread::Destruct(this);
+}