build: move libcc patches to electron repo (#14104)

In the GN build, libchromiumcontent is no longer a distinct library, but
merely a container for a set of scripts and patches. Maintaining those
patches in a separate repository is tedious and error-prone, so merge
them into the main repo.

Once this is merged and GN is the default way to build Electron, the
libchromiumcontent repository can be archived.

patches/common/chromium/dom_storage_map.patch

@@ -0,0 +1,17 @@
+diff --git a/content/common/dom_storage/dom_storage_map.cc b/content/common/dom_storage/dom_storage_map.cc
+index 0a6b0176a982..35a1c3c11a58 100644
+--- a/content/common/dom_storage/dom_storage_map.cc
++++ b/content/common/dom_storage/dom_storage_map.cc
+@@ -182,10 +182,12 @@ bool DOMStorageMap::SetItemInternal(MapType* map_type,
+   size_t new_item_size = size_in_storage(key, value);
+   size_t new_storage_used = storage_used_ - old_item_size + new_item_size;
+ 
++#if 0  // Disable localStorage size limit for Electron.
+   // Only check quota if the size is increasing, this allows
+   // shrinking changes to pre-existing files that are over budget.
+   if (new_item_size > old_item_size && new_storage_used > quota_)
+     return false;
++#endif
+ 
+   (*map_type)[key] = value;
+   ResetKeyIterator();