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

ui/base/ime/dummy_text_input_client.h

 // 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.
 
 #ifndef UI_BASE_IME_DUMMY_TEXT_INPUT_CLIENT_H_
 #define UI_BASE_IME_DUMMY_TEXT_INPUT_CLIENT_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 13 matching lines @@
   void SetCompositionText(const CompositionText& composition) override;
   void ConfirmCompositionText() override;
   void ClearCompositionText() override;
   void InsertText(const base::string16& text) override;
   void InsertChar(const KeyEvent& event) override;
   TextInputType GetTextInputType() const override;
   TextInputMode GetTextInputMode() const override;
   base::i18n::TextDirection GetTextDirection() const override;
   int GetTextInputFlags() const override;
   bool CanComposeInline() const override;
+  float GetScaleFactor() const override;
   gfx::Rect GetCaretBounds() const override;
   bool GetCompositionCharacterBounds(uint32_t index,
                                      gfx::Rect* rect) const override;
   bool HasCompositionText() const override;
   bool GetTextRange(gfx::Range* range) const override;
   bool GetCompositionTextRange(gfx::Range* range) const override;
   bool GetSelectionRange(gfx::Range* range) const override;
   bool SetSelectionRange(const gfx::Range& range) override;
   bool DeleteRange(const gfx::Range& range) override;
   bool GetTextFromRange(const gfx::Range& range,
@@ skipping 22 matching lines @@
   int insert_text_count_;
   int set_composition_count_;
   base::char16 last_insert_char_;
   base::string16 last_insert_text_;
   CompositionText last_composition_;
 };
 
 }  // namespace ui
 
 #endif  // UI_BASE_IME_DUMMY_TEXT_INPUT_CLIENT_H_