Add use_spring_wallpaper flag for Spring default wallpaper

build/common.gypi

Index: build/common.gypi
diff --git a/build/common.gypi b/build/common.gypi
index 5516c63fb77467ce06a27fb98cbce8b1f70b2b7c..d75767ec4e793d2578e63bbd74bd6ee0eed35cd6 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -347,6 +347,9 @@
       # Enables autofill dialog and associated features; disabled by default.
       'enable_autofill_dialog%' : 0,
 
+      # Uses spring wallpaper resources on Spring.
+      'use_spring_wallpaper%': 0,
+
       # Uses OEM-specific wallpaper resources on Chrome OS.
       'use_oem_wallpaper%': 0,
 
@@ -792,6 +795,7 @@
     'enable_session_service%': '<(enable_session_service)',
     'enable_themes%': '<(enable_themes)',
     'enable_autofill_dialog%': '<(enable_autofill_dialog)',
+    'use_spring_wallpaper%': '<(use_spring_wallpaper)',
     'use_oem_wallpaper%': '<(use_oem_wallpaper)',
     'enable_background%': '<(enable_background)',
     'linux_use_gold_binary%': '<(linux_use_gold_binary)',
@@ -1543,6 +1547,9 @@
       ['enable_themes==1', {
         'grit_defines': ['-D', 'enable_themes'],
       }],
+      ['use_spring_wallpaper==1', {
+        'grit_defines': ['-D', 'use_spring_wallpaper'],
+      }],
       ['use_oem_wallpaper==1', {
         'grit_defines': ['-D', 'use_oem_wallpaper'],
       }],