Use the physical-pixel space for native IME on linux platform.

components/arc/ime/arc_ime_service.cc

 // Copyright 2016 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 "components/arc/ime/arc_ime_service.h"
 
 #include <utility>
 
 #include "base/logging.h"
 #include "base/strings/utf_string_conversions.h"
@@ skipping 255 matching lines @@
   if (!is_control_char && !ui::IsSystemKeyModifier(event.flags())) {
     has_composition_text_ = false;
     ime_bridge_->SendInsertText(base::string16(1, event.GetText()));
   }
 }
 
 ui::TextInputType ArcImeService::GetTextInputType() const {
   return ime_type_;
 }
 
+float ArcImeService::GetScaleFactor() const {
+  return 1.0f;

[Shu Chen, 2016/12/22 01:12:23]

There might be a TODO for this.

+}
+
 gfx::Rect ArcImeService::GetCaretBounds() const {
   if (focused_arc_window_.windows().empty())
     return gfx::Rect();
   aura::Window* window = focused_arc_window_.windows().front();
 
   // |cursor_rect_| holds the rectangle reported from ARC apps, in the "screen
   // coordinates" in ARC, counted by physical pixels.
   // Chrome OS input methods expect the coordinates in Chrome OS screen, within
   // device independent pixels. Two factors are involved for the conversion.
 
@@ skipping 64 matching lines @@
     base::i18n::TextDirection direction) {
   return false;
 }
 
 bool ArcImeService::IsTextEditCommandEnabled(
     ui::TextEditCommand command) const {
   return false;
 }
 
 }  // namespace arc