Revert of Revert of Turn on icu_use_data_file_flag on CrOS...

Revert of Revert of Turn on icu_use_data_file_flag on CrOS (https://codereview.chromium.org/165593002/)

Reason for revert:
https://chromium-review.googlesource.com/#/c/185937/ just got landed and this CL can go in now. 

Original issue's description:
> Revert of Turn on icu_use_data_file_flag on CrOS (https://codereview.chromium.org/163793004/)
> 
> Reason for revert:
> https://chromium-review.googlesource.com/#/c/185937/ has to go in first. 
> 
> 
> Original issue's description:
> > Turn on icu_use_data_file_flag on CrOS
> > 
> > See also https://chromium-review.googlesource.com/#/c/185937/
> > 
> > The switch has to be turned on in two places (chromeos-chrome.ebuild and
> > build/common.gypi). One or the other can get landed separately, though.
> > 
> > BUG=72633
> > TEST=net_unittests:*IDN* and base_unittests:*String*
> > TBR=mark
> > 
> > Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=251213
> 
> TBR=mark@chromium.org
> NOTREECHECKS=true
> NOTRY=true
> BUG=72633
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=251214

TBR=mark@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=72633

Review URL: https://codereview.chromium.org/164333003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251220 0039d316-1c4b-4281-b951-d872f2087c98

build/common.gypi

@@ -1332,8 +1332,10 @@
             # can use breakpad for these builds.
             'release_unwind_tables%': 0,
           }],
-          # TODO(jungshik): Turn this on on Android and Chrome OS
-          ['OS!="android" and chromeos==0', {
+          # TODO(jungshik): Turn this on on Android.
+          # For ChromeOS, this should be turned on in chromeos-chrome.ebuild
+          # file as well by adding icu_use_data_file_flag=1 to BUILD_DEFINES.
+          ['OS!="android"', {
             'icu_use_data_file_flag%': 1,
           }],
         ],