[gn] Port icu_use_data_file_flag in gn

BUG=chromium:474921
LOG=n
NOTRY=true

Review-Url: https://codereview.chromium.org/1988023003
Cr-Commit-Position: refs/heads/master@{#36329}

BUILD.gn

@@ -18,6 +18,10 @@ import("//build_overrides/v8.gni")
 import("snapshot_toolchain.gni")
 
 declare_args() {
+  # Use ICU data file (icudtl.dat) if true or library (shared on windows,
+  # static otherwise).
+  icu_use_data_file_flag = true
+
   # Enable the snapshot feature, for fast context creation.
   # http://v8project.blogspot.com/2015/09/custom-startup-snapshots.html
   v8_use_snapshot = true
@@ -1836,8 +1840,13 @@ v8_source_set("v8_base") {
       deps += [ "//third_party/icu:icudata" ]
     }
 
-    # TODO(jochen): Add support for icu_use_data_file_flag
+    if (icu_use_data_file_flag) {
       defines += [ "ICU_UTIL_DATA_IMPL=ICU_UTIL_DATA_FILE" ]
+    } else if (is_win) {
+      defines += [ "ICU_UTIL_DATA_IMPL=ICU_UTIL_DATA_SHARED" ]
+    } else {
+      defines += [ "ICU_UTIL_DATA_IMPL=ICU_UTIL_DATA_STATIC" ]
+    }
   } else {
     sources -= [
       "src/i18n.cc",

build_overrides/v8.gni

@@ -22,6 +22,7 @@ if (((v8_target_arch == "ia32" ||
   v8_enable_gdbjit = true
 }
 
+icu_use_data_file_flag = false
 v8_imminent_deprecation_warnings = true
 v8_optimized_debug = false
 v8_extra_library_files = []

src/v8.gyp

@@ -1603,18 +1603,8 @@
           'dependencies': [
             '<(icu_gyp_path):icui18n',
             '<(icu_gyp_path):icuuc',
-          ]
-        }, {  # v8_enable_i18n_support==0
-          'sources!': [
-            'i18n.cc',
-            'i18n.h',
-          ],
-        }],
-        ['OS=="win" and v8_enable_i18n_support==1', {
-          'dependencies': [
-            '<(icu_gyp_path):icudata',
           ],
-        }],
+          'conditions': [
             ['icu_use_data_file_flag==1', {
               'defines': ['ICU_UTIL_DATA_IMPL=ICU_UTIL_DATA_FILE'],
             }, { # else icu_use_data_file_flag !=1
@@ -1627,6 +1617,18 @@
               ],
             }],
           ],
+        }, {  # v8_enable_i18n_support==0
+          'sources!': [
+            'i18n.cc',
+            'i18n.h',
+          ],
+        }],
+        ['OS=="win" and v8_enable_i18n_support==1', {
+          'dependencies': [
+            '<(icu_gyp_path):icudata',
+          ],
+        }],
+      ],
     },
     {
       'target_name': 'v8_libbase',