Fix chrome_java FindBugs errors found when switching to n sdk.

chrome/android/java/src/org/chromium/chrome/browser/crash/CrashFileManager.java

Index: chrome/android/java/src/org/chromium/chrome/browser/crash/CrashFileManager.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/crash/CrashFileManager.java b/chrome/android/java/src/org/chromium/chrome/browser/crash/CrashFileManager.java
index 82bcb700c037624dcbae605c6aa9367ee4abd6ac..f7c4679b3a2c2179a2c66aa8f9d95d44d717789c 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/crash/CrashFileManager.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/crash/CrashFileManager.java
@@ -4,6 +4,8 @@
 
 package org.chromium.chrome.browser.crash;
 
+import android.support.annotation.Nullable;
+
 import org.chromium.base.Log;
 import org.chromium.base.VisibleForTesting;
 
@@ -102,7 +104,7 @@ public class CrashFileManager {
     }
 
     public File[] getMinidumpWithoutLogcat() {
-        return getMatchingFiles(MINIDUMP_FIRST_TRY_PATTERN);
+        return listCrashFiles(MINIDUMP_FIRST_TRY_PATTERN);
     }
 
     public static boolean isMinidumpMIMEFirstTry(String path) {
@@ -239,35 +241,12 @@ public class CrashFileManager {
     }
 
     /**
-     * Returns all minidump files that could still be uploaded through the normal pipeline.
-     * I.e. forced uploads are not included. Only returns files that we have tried to upload less
-     * than {@param maxTries} number of times.
-     */
-    public File[] getAllMinidumpFiles(int maxTries) {
-        return getFilesBelowMaxTries(getMatchingFiles(MINIDUMP_PATTERN), maxTries);
-    }
-
-    /**
      * Returns all minidump files that could still be uploaded, sorted by modification time stamp.
      * Forced uploads are not included. Only returns files that we have tried to upload less
      * than {@param maxTries} number of times.
      */
-    public File[] getAllMinidumpFilesSorted(int maxTries) {
-        File[] minidumps = getAllMinidumpFiles(maxTries);
-        Arrays.sort(minidumps, sFileComparator);
-        return minidumps;
-    }
-
-    @VisibleForTesting
-    protected File[] getAllFilesSorted() {
-        File crashDir = getCrashDirectoryIfExists();
-        if (crashDir == null) {
-            return new File[] {};
-        }
-
-        File[] files = crashDir.listFiles();
-        Arrays.sort(files, sFileComparator);
-        return files;
+    public File[] getAllMinidumpFiles(int maxTries) {
+        return getFilesBelowMaxTries(listCrashFiles(MINIDUMP_PATTERN), maxTries);
     }
 
     public void cleanOutAllNonFreshMinidumpFiles() {
@@ -279,7 +258,7 @@ public class CrashFileManager {
         }
 
         Set<String> recentCrashes = new HashSet<String>();
-        for (File f : getAllFilesSorted()) {
+        for (File f : listCrashFiles(null)) {
             // The uploads.log file should always be preserved, as it stores the metadata that
             // powers the chrome://crashes UI.
             if (f.getName().equals(CRASH_DUMP_LOGFILE)) {
@@ -313,7 +292,7 @@ public class CrashFileManager {
      */
     @VisibleForTesting
     static File[] getFilesBelowMaxTries(File[] unfilteredFiles, int maxTries) {
-        List<File> filesBelowMaxTries = new ArrayList<>();
+        List<File> filesBelowMaxTries = new ArrayList<>(unfilteredFiles.length);

[Ilya Sherman, 2016/10/15 00:02:53]

nit: This change seems unrelated to the rest of the CL, and didn't seem to be
mentioned in the CL description.  Or, did I miss the reason for this?

         for (File file : unfilteredFiles) {
             if (readAttemptNumber(file.getName()) < maxTries) {
                 filesBelowMaxTries.add(file);
@@ -323,26 +302,30 @@ public class CrashFileManager {
     }
 
     @VisibleForTesting
-    File[] getMatchingFiles(final Pattern pattern) {
-        // Get dump dir and get all files with specified suffix. The path
-        // constructed here must match chrome_paths.cc (see case
-        // chrome::DIR_CRASH_DUMPS).
-        File crashDir = getCrashDirectoryIfExists();
-        if (crashDir == null) {
+    File[] listCrashFiles(@Nullable final Pattern pattern) {

[Ilya Sherman, 2016/10/15 00:02:53]

What does the "crash" in this method name mean?

[Ilya Sherman, 2016/10/15 00:02:53]

Please add documentation for this method.  In particular, it's not obvious that
the returned values are sorted.  (And, it's not really clear to me why you
decided to make all calls to this method return files in sorted order -- just to
share more code?)

+        File crashDir = getCrashDirectory();
+
+        FilenameFilter filter = null;
+        if (pattern != null) {
+            filter = new FilenameFilter() {
+                @Override
+                public boolean accept(File dir, String filename) {
+                    return pattern.matcher(filename).find();
+                }
+            };
+        }
+        File[] minidumps = crashDir.listFiles(filter);

[Ilya Sherman, 2016/10/15 00:02:53]

It's not really correct to name this variable "minidumps" -- there are
non-minidump files present in the crash directory as well.

+        if (minidumps == null) {
+            Log.w(TAG, crashDir.getAbsolutePath() + " does not exist or is not a directory");
             return new File[] {};
         }
-        File[] minidumps = crashDir.listFiles(new FilenameFilter() {
-            @Override
-            public boolean accept(File dir, String filename) {
-                return pattern.matcher(filename).find();
-            }
-        });
+        Arrays.sort(minidumps, sFileComparator);
         return minidumps;
     }
 
     @VisibleForTesting
     File[] getAllUploadedFiles() {
-        return getMatchingFiles(UPLOADED_MINIDUMP_PATTERN);
+        return listCrashFiles(UPLOADED_MINIDUMP_PATTERN);
     }
 
     @VisibleForTesting
@@ -350,20 +333,6 @@ public class CrashFileManager {
         return new File(mCacheDir, CRASH_DUMP_DIR);
     }
 
-    @VisibleForTesting
-    File getCrashDirectoryIfExists() {
-        File crashDirectory = getCrashDirectory();
-        if (!crashDirectory.exists()) {
-            Log.w(TAG, crashDirectory.getAbsolutePath() + " does not exist!");
-            return null;
-        }
-        if (!crashDirectory.isDirectory()) {
-            Log.w(TAG, crashDirectory.getAbsolutePath() + " is not a directory!");
-            return null;
-        }
-        return crashDirectory;
-    }
-
     public File createNewTempFile(String name) throws IOException {
         File f = new File(getCrashDirectory(), name);
         if (f.exists()) {
@@ -390,7 +359,7 @@ public class CrashFileManager {
      * @return The matching File, or null if no matching file is found.
      */
     File getCrashFileWithLocalId(String localId) {
-        for (File f : getAllFilesSorted()) {
+        for (File f : listCrashFiles(null)) {
             // Only match non-uploaded or previously skipped files. In particular, do not match
             // successfully uploaded files; nor files which are not minidump files, such as logcat
             // files.
@@ -413,6 +382,6 @@ public class CrashFileManager {
     }
 
     private File[] getAllTempFiles() {
-        return getMatchingFiles(TMP_PATTERN);
+        return listCrashFiles(TMP_PATTERN);
     }
 }