Add a function to layout.h for getting ScaleFactor of the native view.

ui/base/layout.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/layout.h"
 
 #include <cmath>
 #include <limits>
 
 #include "base/basictypes.h"
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "build/build_config.h"
 #include "ui/base/ui_base_switches.h"
 
+#if defined(USE_AURA) && !defined(OS_WIN)
+#include "ui/aura/root_window.h"
+#include "ui/compositor/compositor.h"
+#endif  // defined(USE_AURA) && !defined(OS_WIN)
+
 #if defined(USE_AURA) && defined(USE_X11)
 #include "ui/base/touch/touch_factory.h"
 #endif // defined(USE_AURA) && defined(USE_X11)
 
 #if defined(OS_WIN)
 #include "base/win/metro.h"
 #include <Windows.h>
 #endif  // defined(OS_WIN)
 
 namespace {
@@ skipping 40 matching lines @@
 
   return has_touch_device;
 #else
   return false;
 #endif
 }
 
 const float kScaleFactorScales[] = {1.0, 2.0};
 const size_t kScaleFactorScalesLength = arraysize(kScaleFactorScales);
 
-#if defined(OS_MACOSX)
-std::vector<ui::ScaleFactor>& GetSupportedScaleFactorsInternal() {
-  static std::vector<ui::ScaleFactor>* supported_scale_factors =
-      new std::vector<ui::ScaleFactor>();
-  if (supported_scale_factors->empty()) {
-      supported_scale_factors->push_back(ui::SCALE_FACTOR_100P);
-      supported_scale_factors->push_back(ui::SCALE_FACTOR_200P);
-  }
-  return *supported_scale_factors;
-}
-#endif  // OS_MACOSX
-
 }  // namespace
 
 namespace ui {
 
 // Note that this function should be extended to select
 // LAYOUT_TOUCH when appropriate on more platforms than just
 // Windows and Ash.
 DisplayLayout GetDisplayLayout() {
 #if defined(USE_ASH)
   if (UseTouchOptimizedUI())
@@ skipping 18 matching lines @@
       smallest_diff = diff;
     }
   }
   return static_cast<ui::ScaleFactor>(closest_match);
 }
 
 float GetScaleFactorScale(ScaleFactor scale_factor) {
   return kScaleFactorScales[scale_factor];
 }
 
-#if defined(OS_MACOSX)
-std::vector<ScaleFactor> GetSupportedScaleFactors() {
-  return GetSupportedScaleFactorsInternal();
+#if !defined(OS_MACOSX)
+ScaleFactor GetScaleFactorForNativeView(gfx::NativeView view) {
+#if defined(USE_AURA) && !defined(OS_WIN)
+  return GetScaleFactorFromScale(
+      view->GetRootWindow()->compositor()->device_scale_factor());
+#else
+  NOTIMPLEMENTED();
+  return SCALE_FACTOR_NONE;
+#endif
 }
-
-namespace test {
-
-void SetSupportedScaleFactors(
-    const std::vector<ui::ScaleFactor>& scale_factors) {
-  std::vector<ui::ScaleFactor>& supported_scale_factors =
-      GetSupportedScaleFactorsInternal();
-  supported_scale_factors.clear();
-
-  for (size_t i = 0; i < scale_factors.size(); ++i)
-    supported_scale_factors.push_back(scale_factors[i]);
-}
-
-}  // namespace test
-
-#endif  // OS_MACOSX
+#endif  // !defined(OS_MACOSX)
 
 }  // namespace ui