Switch to LayoutThemeMobile when emulating mobile device in DevTools.

third_party/WebKit/Source/core/BUILD.gn

 # Copyright 2014 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.
 
 import("//build/config/chrome_build.gni")
 import("//build/config/ui.gni")
 import("//third_party/WebKit/Source/bindings/bindings.gni")
 import("//third_party/WebKit/Source/bindings/core/v8/generated.gni")
 import("//third_party/WebKit/Source/bindings/modules/modules.gni")
 import("//third_party/WebKit/Source/bindings/modules/v8/generated.gni")
@@ skipping 220 matching lines @@
 
   cflags = []
   libs = []
 
   deps = [
     ":prerequisites",
   ]
 
   if (is_win) {
     cflags += [ "/wd4334" ]
+    sources -= [ "layout/LayoutThemeFontProviderDefault.cpp" ]

[pdr., 2016/02/12 06:36:14]

I'm a little out of my depth with these build changes. My worry is the impact on
binary size.

[dgozman, 2016/02/19 19:15:16]

Latest patch makes a 16KB difference on my linux release build.

   } else {  # !is_win
     sources -= [
       "layout/LayoutThemeFontProviderWin.cpp",
       "layout/LayoutThemeWin.cpp",
       "layout/LayoutThemeWin.h",
     ]
   }
+
   if (!is_linux) {
     sources -= [
       "layout/LayoutThemeLinux.cpp",
       "layout/LayoutThemeLinux.h",
     ]
-    if (!is_android) {
-      sources -= [ "layout/LayoutThemeFontProviderLinux.cpp" ]
-    }
   }
 
   if (!is_android) {
     sources -= [
       "layout/LayoutThemeAndroid.cpp",
       "layout/LayoutThemeAndroid.h",
     ]
   }
 
   if (is_mac) {
-    sources -= [
-      "layout/LayoutThemeDefault.cpp",
-      "layout/LayoutThemeDefault.h",
-      "layout/LayoutThemeFontProvider.cpp",
-      "layout/LayoutThemeFontProvider.h",
-      "paint/ThemePainterDefault.cpp",
-      "paint/ThemePainterDefault.h",
-    ]
     libs += [ "Carbon.framework" ]
   } else {  # !is_mac
     sources -= [ "editing/commands/SmartReplaceCF.cpp" ]
   }
 }
 
 # GYP version: //third_party/WebKit/Source/core/core.gyp:webcore_rendering
 source_set("rendering") {
   # The files that go here are currently in "remaining".
 }
@@ skipping 743 matching lines @@
     "$blink_core_output_dir/{{source_name_part}}.h",
   ]
   args = [
     "{{source}}",
     rel_blink_core_gen_dir,
     bison_exe,
   ]
 
   deps = make_core_generated_deps
 }