chore: use mv3 in the stable channel

This CL makes the extension use Manifest Version 3 in the stable channel
for Chrome.

The MV3 builds are mature enough, since the extension has been built
with MV3 in the beta and canary channels for a long time. And this
change is necessary since we're near the MV2 deadline.

Fixed: twpowertools:83
Change-Id: I76db6ba892ca8e0dfafcad5772747f1bc78b5e3b
diff --git a/Makefile b/Makefile
index 7cb4294..91086df 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,4 @@
-.PHONY: node_deps clean_dist deps clean_deps lit_localize_extract lit_localize_build lit_localize_all serve_chromium serve_chromium_mv3 serve_gecko release release_chromium_stable release_chromium_beta release_chromium_canary release_gecko_stable build_test_extension clean_releases test clean trigger_nightly_build
+.PHONY: node_deps clean_dist deps clean_deps lit_localize_extract lit_localize_build lit_localize_all serve_chromium_mv3 serve_gecko release release_chromium_stable release_chromium_beta release_chromium_canary release_gecko_stable build_test_extension clean_releases test clean trigger_nightly_build
 
 WEBPACK := ./node_modules/webpack-cli/bin/cli.js
 JEST := node --experimental-vm-modules ./node_modules/jest/bin/jest.js
@@ -31,9 +31,6 @@
 
 lit_localize_all: lit_localize_extract lit_localize_build
 
-serve_chromium: deps
-	$(WEBPACK) --mode development --env browser_target=chromium --watch
-
 serve_chromium_mv3: deps
 	$(WEBPACK) --mode development --env browser_target=chromium_mv3 --watch
 
@@ -43,9 +40,9 @@
 release: release_chromium_stable release_chromium_beta release_gecko_stable
 
 release_chromium_stable: deps
-	$(WEBPACK) --mode production --env browser_target=chromium
-	$(RELEASE_SCRIPT) -c stable -b chromium
-	rm -rf dist/chromium
+	$(WEBPACK) --mode production --env browser_target=chromium_mv3
+	$(RELEASE_SCRIPT) -c stable -b chromium_mv3
+	rm -rf dist/chromium_mv3
 
 release_chromium_beta: deps
 	$(WEBPACK) --mode production --env browser_target=chromium_mv3
diff --git a/docs/developers/build.md b/docs/developers/build.md
index f9b35f1..5db0b65 100644
--- a/docs/developers/build.md
+++ b/docs/developers/build.md
@@ -21,9 +21,9 @@
 
 ## Build the extension continously with webpack development mode
 If you're developing the extension, you might want to load it into your browser
-without having to constantly build it manually after each change. In order to do
-that, you can run `make serve_chromium`, `make serve_chromium_mv3` or
-`make serve_gecko` depending on the type of continuous build you want.
+without having to constantly build it manually after each change. In order to
+do that, you can run `make serve_chromium_mv3` or `make serve_gecko` depending
+on the type of continuous build you want.
 
 This will run webpack with watch mode and continuously serve a fresh version of
 the compiled extension at `dist/{BROWSER}`, where `{BROWSER}` depends on the
@@ -33,14 +33,3 @@
 Keep in mind that while the extension is continuously built, it is not
 automatically being loaded into Chrome. You'll have to reload the extension
 manually in Chrome (but at least you won't have to both build and reload it).
-
-## About the _Chromium MV3_ target
-Chromium announced a while back a
-[new version of the manifest.json file](https://developer.chrome.com/docs/extensions/mv3/intro/),
-which also introduces some changes to the extension APIs. The _Chromium MV3_
-target builds the extension using this new version.
-
-[MV2 will phase out in January 2023](https://developer.chrome.com/docs/extensions/mv3/mv2-sunset/),
-so starting with version v2.1.2, the CWS beta channel will receive the MV3
-variant of the extension to begin testing it publicly. For now, the stable
-channel will continue to receive the MV2 variant of the extension.