Metro/HiDPI: Move 1x icons into separate pak file

build/common.gypi

Index: build/common.gypi
diff --git a/build/common.gypi b/build/common.gypi
index 429438efb7a5a6686e26fb42995553350b926159..db5bf662d30735af777d891a9887c975e5aea19a 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -40,6 +40,9 @@
 
           # Disable viewport meta tag by default.
           'enable_viewport%': 0,
+
+          # Enable HiDPI support.
+          'enable_hidpi%': 0,
         },
         # Copy conditionally-set variables out one scope.
         'chromeos%': '<(chromeos)',
@@ -49,6 +52,7 @@
         'use_openssl%': '<(use_openssl)',
         'use_virtual_keyboard%': '<(use_virtual_keyboard)',
         'enable_viewport%': '<(enable_viewport)',
+        'enable_hidpi%': '<(enable_hidpi)',
 
         # Compute the architecture that we're building on.
         'conditions': [
@@ -82,6 +86,11 @@
           }, {
             'toolkit_views%': 0,
           }],
+
+          # Enable HiDPI on Mac OS.
+          ['OS=="mac"', {
+            'enable_hidpi%': 1,
+          }],
         ],
       },
 
@@ -95,6 +104,7 @@
       'use_openssl%': '<(use_openssl)',
       'use_virtual_keyboard%': '<(use_virtual_keyboard)',
       'enable_viewport%': '<(enable_viewport)',
+      'enable_hidpi%': '<(enable_hidpi)',
 
       # We used to provide a variable for changing how libraries were built.
       # This variable remains until we can clean up all the users.
@@ -492,6 +502,7 @@
     'chromeos%': '<(chromeos)',
     'use_virtual_keyboard%': '<(use_virtual_keyboard)',
     'enable_viewport%': '<(enable_viewport)',
+    'enable_hidpi%': '<(enable_hidpi)',
     'use_xi2_mt%':'<(use_xi2_mt)',
     'file_manager_extension%': '<(file_manager_extension)',
     'webui_task_manager%': '<(webui_task_manager)',
@@ -1287,6 +1298,9 @@
       ['notifications==1', {
         'defines': ['ENABLE_NOTIFICATIONS'],
       }],
+      ['enable_hidpi==1', {
+        'defines': ['ENABLE_HIDPI=1'],
+      }],
       ['fastbuild!=0', {
 
         'conditions': [