[Android] Allow setting recently visited search engines as default search engine

chrome/android/java/res/layout/search_engine.xml

Index: chrome/android/java/res/layout/search_engine.xml
diff --git a/chrome/android/java/res/layout/search_engine.xml b/chrome/android/java/res/layout/search_engine.xml
index c447b5e04bb1b19b062edfb0a1e4ba1f3f62a50d..d19c90e5c87173f241514b9f4ed28bd837ac1cd4 100644
--- a/chrome/android/java/res/layout/search_engine.xml
+++ b/chrome/android/java/res/layout/search_engine.xml
@@ -27,7 +27,13 @@
             android:id="@+id/description"
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
-            android:textSize="17sp" />
+            android:textSize="17sp"
+            android:textColor="@color/fre_title_color" />

[Ian Wen, 2016/09/27 04:42:00]

If you want to reuse this color, you should change the name of it. An
alternative is to simply put color constant here, such as #565656.

[ltian, 2016/09/28 19:19:46]

Done.

+        <TextView
+            android:id="@+id/url"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:textSize="15sp" />

[Ian Wen, 2016/09/27 04:42:00]

Preset it to visibility gone?

[ltian, 2016/09/28 19:19:46]

I make it visible as the default setting. Then in SearchEngineAdapater, it will
be set as gone if the search engine is prepopulated.

         <TextView
             android:id="@+id/link"
             android:layout_width="wrap_content"