Use precompiled headers on Windows only when a flag is set.

chrome/installer/mini_installer.gyp

Index: chrome/installer/mini_installer.gyp
diff --git a/chrome/installer/mini_installer.gyp b/chrome/installer/mini_installer.gyp
index 18b39f820498041ec72826cee2a885179418cc1e..4f73b983c868e1e3353eab0790dfc0507c07de45 100644
--- a/chrome/installer/mini_installer.gyp
+++ b/chrome/installer/mini_installer.gyp
@@ -175,21 +175,12 @@
         {
           'target_name': 'mini_installer',
           'type': 'executable',
-          'configurations': {
-            'Debug': {
-              # Disable precompiled headers for this project, to avoid
-              # linker errors when building with VS 2008.
-              #
-              # Note that putting this in the 'target_defaults'
-              # section earlier in the file does not successfully
-              # override the 'target_defaults' brought in by the
-              # build/win_precompile.gypi file, so the overriding
-              # needs to be done here, directly in the mini_installer
-              # target.
-              'msvs_precompiled_header': '',
-              'msvs_precompiled_source': '',
-            },
-          },
+
+          # Disable precompiled headers for this project, to avoid
+          # linker errors when building with VS 2008.
+          'msvs_precompiled_header': '',
+          'msvs_precompiled_source': '',
+
           'sources': [
             'mini_installer/chrome.release',
             'mini_installer/chrome_appid.cc',