Makes sure the keyboard typing isn't blocked when InputMethod::OnFocus() is not correctly called.

ui/base/ime/input_method_auralinux.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/base/ime/input_method_auralinux.h"
 
 #include "base/auto_reset.h"
 #include "base/environment.h"
 #include "ui/base/ime/linux/linux_input_method_context_factory.h"
 #include "ui/base/ime/text_input_client.h"
@@ skipping 28 matching lines @@
 
 bool InputMethodAuraLinux::OnUntranslatedIMEMessage(
     const base::NativeEvent& event,
     NativeEventResult* result) {
   return false;
 }
 
 void InputMethodAuraLinux::DispatchKeyEvent(ui::KeyEvent* event) {
   DCHECK(event->type() == ET_KEY_PRESSED || event->type() == ET_KEY_RELEASED);
   DCHECK(system_toplevel_window_focused());
+  if (!system_toplevel_window_focused()) {
+    LOG(ERROR) <<
+        "Key event got without the top-level window being activated.";

[sky, 2016/01/07 16:24:42]

Under what conditions does this happen? It seems like you're working around a
bug in the rest of the code.

[Shu Chen, 2016/01/08 02:04:11]

Yes, exactly. crbug.com/569339 causes a lot of complaints, but it is hard to
repro.
The log here is help us to hunt down the root cause.
I'm trying to add more logs at multiple places and put those logs here (I will
upload a new patch soon).

The following OnFocus() call is to ease the pain for users (the bug can cause
user lose I think).

[yukawa, 2016/01/08 02:21:20]

My understanding is the same to what Shu explained.  Given that we have
sufficient reporters in crbug.com/569339 who can relatively easily reproduce
this issue, having only logging code in this CL is also fine to me.

+    // There are random issues that the keyboard typing doesn't work.
+    // The root cause might be the InputMethod::OnFocus() is not correctly
+    // called when the top-level window is activated
+    // (in DNWA::HandleActivationChanged).
+    // Calls OnFocus here to unblock the keyboard typing.
+    OnFocus();
+  }
 
   // If no text input client, do nothing.
   if (!GetTextInputClient()) {
     ignore_result(DispatchKeyEventPostIME(event));
     return;
   }
 
   suppress_next_result_ = false;
   composition_changed_ = false;
   result_text_.clear();
@@ skipping 300 matching lines @@
 
 void InputMethodAuraLinux::ConfirmCompositionText() {
   TextInputClient* client = GetTextInputClient();
   if (client && client->HasCompositionText())
     client->ConfirmCompositionText();
 
   ResetContext();
 }
 
 }  // namespace ui