Fix "favicon_core" target on iOS.

FallbackIconService depends on gfx::Canvas that is not implemented
on iOS, so remove components/favicon/core/fallback_icon_service.cc
from the build on iOS.

The compilation was not broken before because favicon_core is a
static_library and no symbols of fallback_icon_service.o was used
on iOS and the file was dropped at link time.

Remove incorrect file exclusion in "favicon_content" target.

BUG=None

Review URL: https://codereview.chromium.org/1413373008

Cr-Commit-Position: refs/heads/master@{#358081}
diff --git a/components/favicon.gypi b/components/favicon.gypi
index a75c937..71990a82 100644
--- a/components/favicon.gypi
+++ b/components/favicon.gypi
@@ -21,9 +21,6 @@
       ],
       'sources': [
         # Note: sources list duplicated in GN build.
-        'favicon/core/fallback_icon_client.h',
-        'favicon/core/fallback_icon_service.cc',
-        'favicon/core/fallback_icon_service.h',
         'favicon/core/favicon_client.h',
         'favicon/core/favicon_driver.cc',
         'favicon/core/favicon_driver.h',
@@ -44,6 +41,15 @@
       'include_dirs': [
         '..',
       ],
+      'conditions': [
+        ['OS!="ios"', {
+          'sources': [
+            'favicon/core/fallback_icon_client.h',
+            'favicon/core/fallback_icon_service.cc',
+            'favicon/core/fallback_icon_service.h',
+          ],
+        }],
+      ],
     },
   ],
   'conditions': [
@@ -71,11 +77,6 @@
           'include_dirs': [
             '..',
           ],
-          'sources!': [
-            'favicon/core/fallback_icon_client.h',
-            'favicon/core/fallback_icon_service.cc',
-            'favicon/core/fallback_icon_service.h',
-          ],
         },
       ],
     }],