Add an utility class to improve java logs.

base/android/java/src/org/chromium/base/annotations/NoSideEffects.java

Index: base/android/java/src/org/chromium/base/annotations/NoSideEffects.java
diff --git a/base/android/java/src/org/chromium/base/annotations/NoSideEffects.java b/base/android/java/src/org/chromium/base/annotations/NoSideEffects.java
new file mode 100644
index 0000000000000000000000000000000000000000..803c3f959638f09617af8961fbeb2d3aedffd39e
--- /dev/null
+++ b/base/android/java/src/org/chromium/base/annotations/NoSideEffects.java
@@ -0,0 +1,17 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.base.annotations;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Target;
+
+/**
+ * Annotation used to indicate to proguard methods that have no side effects and can be
+ * safely removed if their return value is not used. This is to be used with
+ * {@link org.chromium.base.Log}'s method, that can also be removed by proguard. That way
+ * expensive calls can be left in debug builds but removed in release.
+ */
+@Target({ElementType.METHOD, ElementType.CONSTRUCTOR})
+public @interface NoSideEffects {}