Add ApiCompatibilityUtils for setImageAlpha.

base/android/java/src/org/chromium/base/ApiCompatibilityUtils.java

Index: base/android/java/src/org/chromium/base/ApiCompatibilityUtils.java
diff --git a/base/android/java/src/org/chromium/base/ApiCompatibilityUtils.java b/base/android/java/src/org/chromium/base/ApiCompatibilityUtils.java
index 44baee4feb4d5a2719de487f568049d3964a47a5..00af5cfc88adb9e2e80f8c27aa8f11cc24fd5230 100644
--- a/base/android/java/src/org/chromium/base/ApiCompatibilityUtils.java
+++ b/base/android/java/src/org/chromium/base/ApiCompatibilityUtils.java
@@ -9,6 +9,7 @@ import android.os.Build;
 import android.view.View;
 import android.view.ViewGroup.MarginLayoutParams;
 import android.view.ViewTreeObserver;
+import android.widget.ImageView;
 import android.widget.RemoteViews;
 import android.widget.TextView;
 
@@ -238,4 +239,15 @@ public class ApiCompatibilityUtils {
             view.getViewTreeObserver().removeGlobalOnLayoutListener(listener);
         }
     }
+
+    /**
+     * @see android.widget.ImageView#setImageAlpha(int)
+     */
+    public static void setImageAlpha(ImageView iv, int alpha) {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
+            iv.setImageAlpha(alpha);
+        } else {
+            iv.setAlpha(alpha);
+        }
+    }
 }