Revert "Fix compilation of official build with Firebase enabled"

This reverts commit 8420c60c.

Reason for revert:

The CL is incorrect as the override of bundle_deps remove necessary dependencies from "chrome" target when firebase is enabled ("//ios/chrome/app/resources" and ios_application_icons_target).

This causes any clobber build with firebase enabled to lack all packed resources, launchscreen xib, ...

Original change's description:
> Fix compilation of official build with Firebase enabled
> 
> Official build with Firebase enabled uses variants to specify
> which Info.plist to use as resource for Firebase. This causes
> a conflict as two bundle_data have the same output path.
> 
> Move the dependency on ios_firebase_resources_target to the
> definition of the "chrome" target, behind the check for use
> of the variants to prevent this conflict.
> 
> Patchset 1 is the original CL http://crrev/c/1250924 by sdefresne
> from which this CL is cloned from.
> 
> TBR=sdefresne@chromium.org, justincohen@chromium.org
> 
> Bug: 845383
> Change-Id: I0e74f04f27708eb970c61b1048cb2492c45cbba4
> Cq-Include-Trybots: luci.chromium.try:ios-simulator-cronet;luci.chromium.try:ios-simulator-full-configs
> Reviewed-on: https://chromium-review.googlesource.com/1252321
> Commit-Queue: Peter Lee <pkl@chromium.org>
> Reviewed-by: Peter Lee <pkl@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#595187}

TBR=sdefresne@chromium.org,justincohen@chromium.org,pkl@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 845383
Change-Id: I23a38548438e05b0b864024e4966cfb5a3168040
Cq-Include-Trybots: luci.chromium.try:ios-simulator-cronet;luci.chromium.try:ios-simulator-full-configs
Reviewed-on: https://chromium-review.googlesource.com/1252483Reviewed-by: Sylvain Defresne <sdefresne@chromium.org>
Commit-Queue: Sylvain Defresne <sdefresne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#595357}

ios/chrome/app/BUILD.gn

@@ -286,20 +286,7 @@ ios_app_bundle("chrome") {
 
   bundle_deps = [ "//ios/chrome/app/resources" ]
   if (!is_chrome_branded || ios_chrome_app_variants == []) {
-    assert(ios_application_icons_target != "",
-           "ios_application_icons_target must be defined.")
     bundle_deps += [ ios_application_icons_target ]
-
-    if (ios_enable_firebase_sdk) {
-      assert(ios_firebase_resources_target != "",
-             "ios_firebase_resources_target must be defined if Firebase SDK " +
-                 "is enabled.")
-
-      # Empty list assigned to bundle_deps to indicate that this is an
-      # intentional override of bundle_deps.
-      bundle_deps = []
-      bundle_deps = [ ios_firebase_resources_target ]
-    }
   } else {
     variants = ios_chrome_app_variants
   }

ios/third_party/firebase/BUILD.gn

@@ -2,7 +2,13 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//ios/third_party/firebase/firebase.gni")
+
 source_set("firebase") {
+  assert(
+      ios_firebase_resources_target != "",
+      "ios_firebase_resources_target must be defined if Firebase SDK is enabled.")
+
   # From gn documentation:
   #   https://chromium.googlesource.com/chromium/src/+/master/tools/gn/docs/reference.md#ldflags
   # "ldflags are NOT pushed to dependents, so applying ldflags to source sets
@@ -13,6 +19,9 @@ source_set("firebase") {
   # This source_set must be specified as a direct deps of an ios_app_bundle
   # target for ldflags specified in :firebase_config to be applied.
   public_configs = [ ":firebase_config" ]
+  deps = [
+    ios_firebase_resources_target,
+  ]
 }
 
 config("firebase_config") {