Fix a findbugs warning - check file.delete return value.

BUG=NONE

Review URL: https://codereview.chromium.org/269603002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@269960 0039d316-1c4b-4281-b951-d872f2087c98

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

@@ -44,7 +44,8 @@ public class TestFileUtil {
 
     public static void deleteFile(String name) {
         File file = new File(name);
-        file.delete();
+        boolean deleted = file.delete();
+        assert (deleted || !file.exists());
     }
 
     /**

build/android/findbugs_filter/findbugs_known_bugs.txt

 H C EC: Using pointer equality to compare a JavaBridgeCoercionTest$CustomType with a JavaBridgeCoercionTest$CustomType2 in org.chromium.content.browser.JavaBridgeCoercionTest.testPassJavaObject()  At JavaBridgeCoercionTest.java
-M B RV: Exceptional return value of java.io.File.delete() ignored in org.chromium.base.test.util.TestFileUtil.deleteFile(String)  At TestFileUtil.java
 M C CSM: Shouldn't use synchronized method, please narrow down the synchronization scope.  At JavaBridgeArrayCoercionTest.java
 M C CSM: Shouldn't use synchronized method, please narrow down the synchronization scope.  At JavaBridgeArrayTest.java
 M C CSM: Shouldn't use synchronized method, please narrow down the synchronization scope.  At JavaBridgeBasicsTest.java