Introduce ThreadedInputConnection behind a switch

content/renderer/input/render_widget_input_handler.cc

 // Copyright 2015 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 "content/renderer/input/render_widget_input_handler.h"
 
 #include <stddef.h>
 #include <stdint.h>
 #include <utility>
 
 #include "base/auto_reset.h"
+#include "base/command_line.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/trace_event/trace_event_synthetic_delay.h"
 #include "build/build_config.h"
 #include "cc/trees/swap_promise_monitor.h"
 #include "components/scheduler/renderer/renderer_scheduler.h"
 #include "content/common/input/input_event_ack.h"
 #include "content/common/input/input_event_ack_state.h"
 #include "content/common/input/web_input_event_traits.h"
+#include "content/public/common/content_switches.h"
 #include "content/renderer/gpu/render_widget_compositor.h"
 #include "content/renderer/ime_event_guard.h"
 #include "content/renderer/input/render_widget_input_handler_delegate.h"
 #include "content/renderer/render_thread_impl.h"
 #include "content/renderer/render_widget.h"
 #include "third_party/WebKit/public/platform/WebFloatPoint.h"
 #include "third_party/WebKit/public/platform/WebFloatSize.h"
 #include "ui/events/latency_info.h"
 #include "ui/gfx/geometry/point_conversions.h"
 
@@ skipping 171 matching lines @@
 
   // Calls into |didOverscroll()| while handling this event will populate
   // |event_overscroll|, which in turn will be bundled with the event ack.
   scoped_ptr<DidOverscrollParams> event_overscroll;
   base::AutoReset<scoped_ptr<DidOverscrollParams>*>
       handling_event_overscroll_resetter(&handling_event_overscroll_,
                                          &event_overscroll);
 
 #if defined(OS_ANDROID)
   bool from_ime = false;
+  bool use_ime_thread = base::CommandLine::ForCurrentProcess()->HasSwitch(
+      switches::kUseImeThread);
 
   // For most keyboard events, we want the change source to be FROM_IME because
   // we don't need to update IME states in AdapterInputConnection.
   if (WebInputEvent::isKeyboardEventType(input_event.type)) {
     const WebKeyboardEvent& key_event =
         *static_cast<const WebKeyboardEvent*>(&input_event);
+    if (use_ime_thread) {
+      // We do not send state update for synthetic keys that accompany
+      // setComposingText / commitText.
+      from_ime = key_event.nativeKeyCode != 229;

[aelias_OOO_until_Jul13, 2016/01/21 07:43:05]

But this line implies you're still setting FROM_IME for character key events
coming from an attached physical keyboard?  That would cause your BlockingQueue
to get out of sync, no?  Anyway, see my proposal in render_widget.cc for a way
to avoid this whole problem space.

[Changwan Ryu, 2016/01/22 10:22:17]

Done. Thanks for finding it! Fixed as suggested!

     // TODO(changwan): this if-condition is a stop-gap solution to update IME
     // states in AdapterInputConnection when using DPAD navigation. This is not
     // a correct solution because InputConnection#getTextBeforeCursor()
     // immediately after InputConnection#sendKeyEvent() will not return the
     // correct value. The correct solution is either redesign the architecture
     // or emulate the DPAD behavior in AdapterInputConnection, either is
     // non-trivial.
-    if (key_event.nativeKeyCode != AKEYCODE_TAB &&
+    } else if (key_event.nativeKeyCode != AKEYCODE_TAB &&
         key_event.nativeKeyCode != AKEYCODE_DPAD_CENTER &&
         key_event.nativeKeyCode != AKEYCODE_DPAD_LEFT &&
         key_event.nativeKeyCode != AKEYCODE_DPAD_RIGHT &&
         key_event.nativeKeyCode != AKEYCODE_DPAD_UP &&
-        key_event.nativeKeyCode != AKEYCODE_DPAD_DOWN)
+        key_event.nativeKeyCode != AKEYCODE_DPAD_DOWN) {
       from_ime = true;
+    }
   }
 
   ImeEventGuard guard(widget_, false, from_ime);
 #endif
 
   base::TimeTicks start_time;
   if (base::TimeTicks::IsHighResolution())
     start_time = base::TimeTicks::Now();
 
   TRACE_EVENT1("renderer,benchmark",
@@ skipping 265 matching lines @@
   if (pending_input_event_ack_) {
     TRACE_EVENT_ASYNC_END0("input",
                            "RenderWidgetInputHandler::ThrottledInputEventAck",
                            pending_input_event_ack_.get());
     delegate_->OnInputEventAck(std::move(pending_input_event_ack_));
   }
   total_input_handling_time_this_frame_ = base::TimeDelta();
 }
 
 }  // namespace content