Android: Do not build any extensions code except for extensions_constants.

chrome/common/BUILD.gn

Index: chrome/common/BUILD.gn
diff --git a/chrome/common/BUILD.gn b/chrome/common/BUILD.gn
index d295f52f8b49d18136024133e292d64cd0f7faba..046475cb3fe871ecc7dedb724229543c8b826fa6 100644
--- a/chrome/common/BUILD.gn
+++ b/chrome/common/BUILD.gn
@@ -24,6 +24,8 @@ grit("resources") {
 
 # GYP version: chrome/chrome_resources.gyp:chrome_resources
 #              (generate_extensions_api_resources action)
+if (enable_extensions) {
+
 grit("extensions_api_resources") {
   source = "extensions_api_resources.grd"
   output_dir = "$root_gen_dir/chrome"
@@ -33,6 +35,8 @@ grit("extensions_api_resources") {
   ]
 }
 
+}
+
 # GYP version: chrome/chrome_common.gyp:common
 static_library("common") {
   sources = rebase_path(gypi_values.chrome_common_sources, ".", "//chrome")
@@ -62,8 +66,7 @@ static_library("common") {
     "//components/variations",
     "//content/public/common",
     "//crypto",
-    "//extensions:extensions_resources",
-    "//extensions/strings",
+    "//extensions/common:common_constants",
     "//media/cast:net",
     "//net",
     "//skia",
@@ -106,6 +109,8 @@ static_library("common") {
       "//chrome/common/extensions/api",
       "//extensions/common",
       "//extensions/common/api",
+      "//extensions:extensions_resources",
+      "//extensions/strings",
     ]
   }
 
@@ -288,8 +293,6 @@ source_set("test_support") {
   visibility = [ "//chrome/test:test_support" ]
 
   sources = [
-    "extensions/extension_test_util.cc",
-    "extensions/extension_test_util.h",
   ]
 
   deps = [
@@ -307,4 +310,11 @@ source_set("test_support") {
     ]
   }
 
+  if (enable_extensions) {
+    sources += [
+      "extensions/extension_test_util.cc",
+      "extensions/extension_test_util.h",
+    ]
+  }
+
 }