Fix and suppress some lint warnings

android_webview/test/shell/res/layout/testshell_activity.xml

Index: android_webview/test/shell/res/layout/testshell_activity.xml
diff --git a/android_webview/test/shell/res/layout/testshell_activity.xml b/android_webview/test/shell/res/layout/testshell_activity.xml
index 0a997fa14d5d2902d83da4040a8d278394abeffc..d4d72e326a65d27f53dc04a38160923960bf93fa 100644
--- a/android_webview/test/shell/res/layout/testshell_activity.xml
+++ b/android_webview/test/shell/res/layout/testshell_activity.xml
@@ -15,30 +15,32 @@
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:orientation="horizontal">
+        <!--suppress LabelFor -->
         <EditText android:id="@+id/url"
             android:layout_width="0dp"
             android:layout_height="wrap_content"
             android:layout_weight="1"
             android:gravity="bottom"
             android:textSize="18sp"
-            android:autoText="true"
-            android:capitalize="sentences"
             android:singleLine="true"
             android:selectAllOnFocus="true"
             android:inputType="textUri"
             android:imeOptions="actionGo" />
         <ImageButton android:id="@+id/prev"
+            android:contentDescription="@null"
             android:layout_width="38dp"
             android:layout_height="38dp"
             android:src="@android:drawable/ic_media_previous"
             android:scaleType="center" />
         <ImageButton android:id="@+id/next"
+            android:contentDescription="@null"
             android:layout_width="38dp"
             android:layout_height="38dp"
             android:src="@android:drawable/ic_media_next"
             android:scaleType="center" />
     </LinearLayout>
     <LinearLayout android:id="@+id/content_container"
+        android:orientation="horizontal"
         android:layout_width="match_parent"
         android:layout_height="match_parent">
     </LinearLayout>