Always add 100P scale format in the supported format list.

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>
 
@@ skipping 55 matching lines @@
 
 const float kScaleFactorScales[] = {1.0f, 1.4f, 1.8f, 2.0f};
 COMPILE_ASSERT(NUM_SCALE_FACTORS == arraysize(kScaleFactorScales),
                kScaleFactorScales_incorrect_size);
 const size_t kScaleFactorScalesLength = arraysize(kScaleFactorScales);
 
 std::vector<ScaleFactor>& GetSupportedScaleFactorsInternal() {
   static std::vector<ScaleFactor>* supported_scale_factors =
       new std::vector<ScaleFactor>();
   if (supported_scale_factors->empty()) {
-#if !defined(OS_IOS)
-    // On platforms other than iOS, 100P is always a supported scale factor.
+    // 100P is always a supported scale factor.
     supported_scale_factors->push_back(SCALE_FACTOR_100P);
-#endif
 
 #if defined(OS_IOS)
+    // TODO(ios): 100p should not be necessary on iOS retina devices. However
+    // the sync service only supports syncing 100p favicons. Until sync supports
+    // other scales 100p is needed in the list of scale factors to retrieve and
+    // store the favicons in both 100p for sync and 200p for display. cr/160503.
     gfx::Display display = gfx::Screen::GetNativeScreen()->GetPrimaryDisplay();
     if (display.device_scale_factor() > 1.0) {
       DCHECK_EQ(2.0, display.device_scale_factor());
       supported_scale_factors->push_back(SCALE_FACTOR_200P);
-    } else {
-      supported_scale_factors->push_back(SCALE_FACTOR_100P);
     }
 #elif defined(OS_MACOSX)
     if (base::mac::IsOSLionOrLater())
       supported_scale_factors->push_back(SCALE_FACTOR_200P);
 #elif defined(OS_WIN) && defined(ENABLE_HIDPI)
     if (base::win::IsMetroProcess() && base::win::IsTouchEnabled()) {
       supported_scale_factors->push_back(SCALE_FACTOR_140P);
       supported_scale_factors->push_back(SCALE_FACTOR_180P);
     }
 #elif defined(USE_ASH)
@@ skipping 81 matching lines @@
   gfx::Screen* screen = gfx::Screen::GetScreenFor(view);
   if (screen->IsDIPEnabled()) {
     gfx::Display display = screen->GetDisplayNearestWindow(view);
     return GetScaleFactorFromScale(display.device_scale_factor());
   }
   return ui::SCALE_FACTOR_100P;
 }
 #endif  // !defined(OS_MACOSX)
 
 }  // namespace ui