Request to start/stop calculating composition info from RenderWidget when it is active/inactive.

content/browser/renderer_host/render_widget_host_view_aura.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 "content/browser/renderer_host/render_widget_host_view_aura.h"
 
 #include <set>
 #include <utility>
 
 #include "base/auto_reset.h"
@@ skipping 450 matching lines @@
 #if defined(OS_WIN)
       legacy_render_widget_host_HWND_(nullptr),
       legacy_window_destroyed_(false),
       virtual_keyboard_requested_(false),
 #endif
       has_snapped_to_boundary_(false),
       is_guest_view_hack_(is_guest_view_hack),
       set_focus_on_mouse_down_or_key_event_(false),
       device_scale_factor_(0.0f),
       disable_input_event_router_for_testing_(false),
+      last_active_widget_process_id_(-1),
+      last_active_widget_routing_id_(MSG_ROUTING_NONE),
       weak_ptr_factory_(this) {
   if (!is_guest_view_hack_)
     host_->SetView(this);
 
   // Let the page-level input event router know about our surface ID
   // namespace for surface-based hit testing.
   if (host_->delegate() && host_->delegate()->GetInputEventRouter()) {
     host_->delegate()->GetInputEventRouter()->AddSurfaceClientIdOwner(
         GetSurfaceClientId(), this);
   }
@@ skipping 2506 matching lines @@
     bool did_update_state) {
   DCHECK_EQ(text_input_manager_, text_input_manager);
 
   if (!GetInputMethod())
     return;
 
   if (did_update_state)
     GetInputMethod()->OnTextInputTypeChanged(this);
 
   const TextInputState* state = text_input_manager_->GetTextInputState();
-
   if (state && state->show_ime_if_needed &&
       state->type != ui::TEXT_INPUT_TYPE_NONE) {
     GetInputMethod()->ShowImeIfNeeded();
-
     // Start monitoring the composition information if the focused node is
     // editable.
-    host_->Send(new InputMsg_RequestCompositionUpdate(
-        host_->GetRoutingID(),
-        false /* immediate request */,
+    RenderWidgetHostImpl* last_active_widget =
+        text_input_manager_->GetActiveWidget();
+    last_active_widget_routing_id_ = last_active_widget->GetRoutingID();
+    last_active_widget_process_id_ = last_active_widget->GetProcess()->GetID();
+    last_active_widget->Send(new InputMsg_RequestCompositionUpdate(
+        last_active_widget->GetRoutingID(), false /* immediate request */,
         true /* monitor request */));
   } else {
     // Stop monitoring the composition information if the focused node is not
     // editable.
-    host_->Send(new InputMsg_RequestCompositionUpdate(
-        host_->GetRoutingID(),
-        false /* immediate request */,
-        false /* monitor request */));
+    if (last_active_widget_routing_id_ != MSG_ROUTING_NONE) {
+      RenderWidgetHostImpl* last_active_widget = RenderWidgetHostImpl::FromID(
+          last_active_widget_process_id_, last_active_widget_routing_id_);

[kenrb, 2016/08/08 19:15:50]

It feels weird to have this RenderWidgetHostView sending an IPC through a
different RenderWidgetHost (i.e. not the RWH for which it is the view), but it
might not be worth trying to do it another way. It doesn't feel important enough
to route it back to TextInputStateManager.

[EhsanK, 2016/08/09 16:42:29]

How about adding a method to RWH? That will be more compatible with the way
TextInputManager is used to use a widget and call the method which send the IPC.

+      if (!last_active_widget)
+        return;

[kenrb, 2016/08/08 19:15:50]

nit: It might be better to have
if (last_active_widget) {
  // [Send IPC, etc]
}

It's a bit more future-friendly, in case somebody tries to add code other code
to the end of this method and doesn't notice the early return here.

[EhsanK, 2016/08/09 16:42:29]

Acknowledged.

+      last_active_widget->Send(new InputMsg_RequestCompositionUpdate(
+          last_active_widget->GetRoutingID(), false /* immediate request */,
+          false /* monitor request */));
+      last_active_widget_process_id_ = MSG_ROUTING_NONE;

[Charlie Reis, 2016/08/08 17:12:01]

You need to clear the routing ID as well, especially since that's what you're
checking for above.  Plus process_id_ should be -1, not MSG_ROUTING_NONE (to be
consistent with the value from the constructor).  

Actually, maybe we should be using ChildProcessHost::kInvalidUniqueID for the
process IDs, though it's not a big deal.

+    }
   }
 }
 
 void RenderWidgetHostViewAura::OnImeCancelComposition(
     TextInputManager* text_input_manager,
     RenderWidgetHostViewBase* view) {
   // |view| is not necessarily the one corresponding to
   // TextInputManager::GetActiveWidget() as RenderWidgetHostViewAura can call
   // this method to finish any ongoing composition in response to a mouse down
   // event.
@@ skipping 39 matching lines @@
 
 ////////////////////////////////////////////////////////////////////////////////
 // RenderWidgetHostViewBase, public:
 
 // static
 void RenderWidgetHostViewBase::GetDefaultScreenInfo(WebScreenInfo* results) {
   GetScreenInfoForWindow(results, NULL);
 }
 
 }  // namespace content