Define crash keys in the directory hierarchy where they are used.

media/base/BUILD.gn

Index: media/base/BUILD.gn
diff --git a/media/base/BUILD.gn b/media/base/BUILD.gn
index 17eaec1083812ada65c2893ae5ad4b273c70d1e2..353463e0cad2483c77fedd674e7ae347e5a5f1d1 100644
--- a/media/base/BUILD.gn
+++ b/media/base/BUILD.gn
@@ -22,6 +22,21 @@ config("base_config") {
   ]
 }
 
+# Target that provides the media component's crash keys publicly without
+# needing to depend on the rest of base.
+source_set("crash_keys") {
+  sources = [
+    "crash_keys.cc",
+    "crash_keys.h",
+  ]
+  deps = [
+    "//base",
+    "//components/crash/core/common",
+  ]
+
+  configs += [ "//media:media_implementation" ]
+}
+
 source_set("base") {
   # This is part of the media component.
   visibility = [ "//media/*" ]
@@ -102,6 +117,8 @@ source_set("base") {
     "channel_mixing_matrix.h",
     "container_names.cc",
     "container_names.h",
+    "crash_keys.cc",
+    "crash_keys.h",
     "data_buffer.cc",
     "data_buffer.h",
     "data_source.cc",
@@ -252,6 +269,7 @@ source_set("base") {
   public_deps = []
   deps = [
     "//base/third_party/dynamic_annotations:dynamic_annotations",
+    "//components/crash/core/common",
     "//gpu",
     "//media:media_features",
     "//media:shared_memory_support",