Merge reused code into a common file

Change-Id: I264aaa67ae1103df2292e17d1eb46b3054799994
diff --git a/templates/manifest.gjson b/templates/manifest.gjson
index 06a9965..e1f6cdb 100644
--- a/templates/manifest.gjson
+++ b/templates/manifest.gjson
@@ -13,7 +13,7 @@
   "content_scripts": [
     {
       "matches": ["https://support.google.com/s/community*"],
-      "js": ["content_scripts/console_inject.js"]
+      "js": ["common/content_scripts_injections.js", "content_scripts/console_inject.js"]
     },
     {
       "matches": ["https://support.google.com/s/community*"],
@@ -26,7 +26,7 @@
     },
     {
       "matches": ["https://support.google.com/*/thread/*"],
-      "js": ["content_scripts/thread_inject.js"],
+      "js": ["common/content_scripts_injections.js", "content_scripts/thread_inject.js"],
       "run_at": "document_end"
     },
     {
@@ -62,7 +62,10 @@
 #if defined(CHROMIUM)
     "persistent": false,
 #endif
-    "scripts": ["background.js"]
+    "scripts": [
+      "common/common.js",
+      "background.js"
+    ]
   },
 #if defined(GECKO)
   "browser_specific_settings": {