Creating new gn arg: enable_all_proguard_optimizations.

content/shell/android/BUILD.gn

Index: content/shell/android/BUILD.gn
diff --git a/content/shell/android/BUILD.gn b/content/shell/android/BUILD.gn
index 95296ccbd5a68490986367fe81a50fde3aebd963..a9336ead0028795387de76d4a0c03302ac9ab9b5 100644
--- a/content/shell/android/BUILD.gn
+++ b/content/shell/android/BUILD.gn
@@ -152,19 +152,21 @@ android_library("content_shell_test_java") {
   ]
 }
 
-instrumentation_test_apk("content_shell_test_apk") {
-  deps = [
-    "//base:base_javatests",
-    "//content/public/android:content_javatests",
-    "//net/android:net_javatests",
-  ]
-  data_deps = [
-    ":content_shell_apk",
-  ]
-  apk_under_test = ":content_shell_apk"
-  apk_name = "ContentShellTest"
-  android_manifest = "javatests/AndroidManifest.xml"
-  isolate_file = "../../content_shell_test_data.isolate"
+if (!enable_all_proguard_optimizations) {
+  instrumentation_test_apk("content_shell_test_apk") {
+    deps = [
+      "//base:base_javatests",
+      "//content/public/android:content_javatests",
+      "//net/android:net_javatests",
+    ]
+    data_deps = [
+      ":content_shell_apk",
+    ]
+    apk_under_test = ":content_shell_apk"
+    apk_name = "ContentShellTest"
+    android_manifest = "javatests/AndroidManifest.xml"
+    isolate_file = "../../content_shell_test_data.isolate"
+  }
 }
 
 if (current_cpu != "x64") {