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

ui/base/ime/input_method_win.cc

 // Copyright (c) 2012 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_win.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include "base/auto_reset.h"
@@ skipping 244 matching lines @@
 }
 
 LRESULT InputMethodWin::OnChar(HWND window_handle,
                                UINT message,
                                WPARAM wparam,
                                LPARAM lparam,
                                const base::NativeEvent& event,
                                BOOL* handled) {
   *handled = TRUE;
 
+  if (!system_toplevel_window_focused()) {
+    LOG(ERROR) <<
+        "Char message got without the top-level window being activated.";

[yukawa, 2016/01/07 11:09:42]

(optional) We can also log |GetActiveWindow() == toplevel_window_handle_| as an
evidence that |system_toplevel_window_focused_| should have been true here.

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

I think ::GetActiveWindow() could return non-top-level window. Right?

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

(just FYI) AFAIK it always returns a top-level window, or NULL.  (We have
actually relied on that API in InputMethodWin::IsWindowFocused()).

[Shu Chen, 2016/01/08 09:00:16]

Done.

+    // 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();
+  }
+
   // We need to send character events to the focused text input client event if
   // its text input type is ui::TEXT_INPUT_TYPE_NONE.
   if (GetTextInputClient()) {
     const base::char16 kCarriageReturn = L'\r';
     const base::char16 ch = static_cast<base::char16>(wparam);
     // A mask to determine the previous key state from |lparam|. The value is 1
     // if the key is down before the message is sent, or it is 0 if the key is
     // up.
     const uint32_t kPrevKeyDownBit = 0x40000000;
     if (ch == kCarriageReturn && !(lparam & kPrevKeyDownBit))
@@ skipping 359 matching lines @@
       enabled_ = true;
       break;
   }
 
   imm32_manager_.SetTextInputMode(window_handle, text_input_mode);
   tsf_inputscope::SetInputScopeForTsfUnawareWindow(
       window_handle, text_input_type, text_input_mode);
 }
 
 }  // namespace ui