Componentize component_updater: Split crx_file code off into its own component.

components/crx_file.gypi

Index: components/crx_file.gypi
diff --git a/components/language_usage_metrics.gypi b/components/crx_file.gypi
similarity index 66%
copy from components/language_usage_metrics.gypi
copy to components/crx_file.gypi
index e150a1bba9e6673d38945da908c9edd17bea6fcc..07a0487c0c77bf1d8236ca036865899cd7f02d03 100644
--- a/components/language_usage_metrics.gypi
+++ b/components/crx_file.gypi
@@ -5,7 +5,7 @@
 {
   'targets': [
     {
-      'target_name': 'language_usage_metrics',
+      'target_name': 'crx_file',
       'type': 'static_library',
       'dependencies': [
         '../base/base.gyp:base',
@@ -13,9 +13,13 @@
       'include_dirs': [
         '..',
       ],
+      'defines': [
+        'CRX_FILE_IMPLEMENTATION',
+      ],
       'sources': [
-        'language_usage_metrics/language_usage_metrics.cc',
-        'language_usage_metrics/language_usage_metrics.h',
+        'crx_file/constants.h',
+        'crx_file/crx_file.cc',
+        'crx_file/crx_file.h',
       ],
     },
   ],