Add pre instrumentation test hooks

base/test/android/javatests/src/org/chromium/base/test/util/CommandLineFlags.java

Index: base/test/android/javatests/src/org/chromium/base/test/util/CommandLineFlags.java
diff --git a/base/test/android/javatests/src/org/chromium/base/test/util/CommandLineFlags.java b/base/test/android/javatests/src/org/chromium/base/test/util/CommandLineFlags.java
index 16697d3fc9704e2c00f9d848012d19352beda489..408074c29f42d5d552120375ad574f984556d364 100644
--- a/base/test/android/javatests/src/org/chromium/base/test/util/CommandLineFlags.java
+++ b/base/test/android/javatests/src/org/chromium/base/test/util/CommandLineFlags.java
@@ -10,6 +10,7 @@
 
 import org.chromium.base.BaseChromiumApplication;
 import org.chromium.base.CommandLine;
+import org.chromium.base.test.BaseTestResult.PreTestHook;
 
 import java.lang.annotation.ElementType;
 import java.lang.annotation.Inherited;
@@ -102,4 +103,14 @@ public static void setUp(Context targetContext, AnnotatedElement element) {
     }
 
     private CommandLineFlags() {}
+
+    public static PreTestHook getRegistrationHook() {
+        return new PreTestHook() {
+            @Override
+            public void run(Context targetContext, Method testMethod) {
+                CommandLineFlags.setUp(targetContext, testMethod);
+            }
+
+        };
+    }
 }