Ensure that extension resources are loaded with the correct scaling applied on Windows.

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 <algorithm>
 #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/touch/touch_device.h"
 #include "ui/base/ui_base_switches.h"
 #include "ui/gfx/display.h"
 #include "ui/gfx/image/image_skia.h"
 #include "ui/gfx/screen.h"
 
 #if defined(OS_WIN)
 #include "base/win/metro.h"
+#include "ui/gfx/win/dpi.h"
 #include <Windows.h>
 #endif  // defined(OS_WIN)
 
 namespace ui {
 
 namespace {
 
 bool ScaleFactorComparator(const ScaleFactor& lhs, const ScaleFactor& rhs){
   return GetImageScale(lhs) < GetImageScale(rhs);
 }
@@ skipping 20 matching lines @@
     } else if (switch_value != switches::kTouchOptimizedUIAuto) {
       LOG(ERROR) << "Invalid --touch-optimized-ui option: " << switch_value;
     }
   }
 
   // We use the touch layout only when we are running in Metro mode.
   return base::win::IsMetroProcess() && ui::IsTouchDevicePresent();
 }
 #endif  // defined(OS_WIN)
 
-const float kScaleFactorScales[] = {1.0f, 1.0f, 1.25f, 1.33f, 1.4f, 1.5f, 1.8f,
-                                    2.0f, 3.0f};
-COMPILE_ASSERT(NUM_SCALE_FACTORS == arraysize(kScaleFactorScales),
+}  // namespace
+
+float g_kScaleFactorScales[] = {1.0f, 1.0f, 1.25f, 1.33f, 1.4f, 1.5f, 1.8f,
+                                2.0f, 3.0f};
+COMPILE_ASSERT(NUM_SCALE_FACTORS == arraysize(g_kScaleFactorScales),
                kScaleFactorScales_incorrect_size);
 
-}  // namespace
-
 DisplayLayout GetDisplayLayout() {
 #if defined(OS_WIN)
   if (UseTouchOptimizedUI())
     return LAYOUT_TOUCH;
 #endif
   return LAYOUT_DESKTOP;
 }
 
 void SetSupportedScaleFactors(
     const std::vector<ui::ScaleFactor>& scale_factors) {
   if (g_supported_scale_factors != NULL)
     delete g_supported_scale_factors;
 
   g_supported_scale_factors = new std::vector<ScaleFactor>(scale_factors);
   std::sort(g_supported_scale_factors->begin(),
             g_supported_scale_factors->end(),
             ScaleFactorComparator);
 
   // Set ImageSkia's supported scales.
   std::vector<float> scales;
   for (std::vector<ScaleFactor>::const_iterator it =
           g_supported_scale_factors->begin();
        it != g_supported_scale_factors->end(); ++it) {
-    scales.push_back(GetImageScale(*it));
+    scales.push_back(g_kScaleFactorScales[*it]);
   }
   gfx::ImageSkia::SetSupportedScales(scales);
 }
 
 const std::vector<ScaleFactor>& GetSupportedScaleFactors() {
   DCHECK(g_supported_scale_factors != NULL);
   return *g_supported_scale_factors;
 }
 
 ScaleFactor GetSupportedScaleFactor(float scale) {
   DCHECK(g_supported_scale_factors != NULL);
   ScaleFactor closest_match = SCALE_FACTOR_100P;
   float smallest_diff =  std::numeric_limits<float>::max();
   for (size_t i = 0; i < g_supported_scale_factors->size(); ++i) {
     ScaleFactor scale_factor = (*g_supported_scale_factors)[i];
-    float diff = std::abs(kScaleFactorScales[scale_factor] - scale);
+    float diff = std::abs(g_kScaleFactorScales[scale_factor] - scale);
     if (diff < smallest_diff) {
       closest_match = scale_factor;
       smallest_diff = diff;
     }
   }
   DCHECK_NE(closest_match, SCALE_FACTOR_NONE);
   return closest_match;
 }
 
 float GetImageScale(ScaleFactor scale_factor) {
-  return kScaleFactorScales[scale_factor];
+#if defined(OS_WIN)
+  if (gfx::IsHighDPIEnabled())
+    return gfx::win::GetDeviceScaleFactor();
+#endif
+  return g_kScaleFactorScales[scale_factor];
 }
 
 bool IsScaleFactorSupported(ScaleFactor scale_factor) {
   DCHECK(g_supported_scale_factors != NULL);
   return std::find(g_supported_scale_factors->begin(),
                    g_supported_scale_factors->end(),
                    scale_factor) != g_supported_scale_factors->end();
 }
 
 // Returns the scale factor closest to |scale| from the full list of factors.
 // Note that it does NOT rely on the list of supported scale factors.
 // Finding the closest match is inefficient and shouldn't be done frequently.
 ScaleFactor FindClosestScaleFactorUnsafe(float scale) {
   float smallest_diff =  std::numeric_limits<float>::max();
   ScaleFactor closest_match = SCALE_FACTOR_100P;
   for (int i = SCALE_FACTOR_100P; i < NUM_SCALE_FACTORS; ++i) {
     const ScaleFactor scale_factor = static_cast<ScaleFactor>(i);
-    float diff = std::abs(kScaleFactorScales[scale_factor] - scale);
+    float diff = std::abs(g_kScaleFactorScales[scale_factor] - scale);
     if (diff < smallest_diff) {
       closest_match = scale_factor;
       smallest_diff = diff;
     }
   }
   return closest_match;
 }
 
 namespace test {
 
@@ skipping 25 matching lines @@
   gfx::Screen* screen = gfx::Screen::GetScreenFor(view);
   if (screen->IsDIPEnabled()) {
     gfx::Display display = screen->GetDisplayNearestWindow(view);
     return GetSupportedScaleFactor(display.device_scale_factor());
   }
   return ui::SCALE_FACTOR_100P;
 }
 #endif  // !defined(OS_MACOSX)
 
 }  // namespace ui