Support content scheme uri for Chrome on Android

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

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.base;
 
 import android.content.ContentResolver;
 import android.content.Context;
 import android.database.Cursor;
 import android.net.Uri;
@@ skipping 64 matching lines @@
     @CalledByNative
     public static boolean contentUriExists(Context context, String uriString) {
         ParcelFileDescriptor pfd = getParcelFileDescriptor(context, uriString);
         if (pfd == null) {
             return false;
         }
         return true;
     }
 
     /**
+     * Retrieve the mime type for the content URI.

[nyquist, 2014/11/19 00:06:25]

Nit: MIME here and below?

[qinmin, 2014/11/19 02:13:07]

Done.

+     *
+     * @param context {@link Context} in interest.
+     * @param uriString the content URI to open.

[nyquist, 2014/11/19 00:06:25]

It feels a bit off that we say 'open' here. Maybe 'inspect' or 'look up'? Or
"the content URI to get the MIME type for"?

[qinmin, 2014/11/19 02:13:07]

Done.

+     * @returns mime type or an empty string if the input params are invalid.

[nyquist, 2014/11/19 00:06:25]

This leads to believe that the method can never return null, which is wrong. It
still returns null if the URL is invalid (I am assuming they also mean
non-existing?).

[palmer, 2014/11/19 00:23:54]

FWIW, The Java Way would be to throw, not return, to signal error.

[qinmin, 2014/11/19 02:13:07]

Ok, changed the description to just return NULL on error and invalid case.

[qinmin, 2014/11/19 02:13:07]

This method is called by native, so either the java side or the native side has
to handle the exception.
Since contentResolver silently returns a NULL if uri is invalid, we will just
return null for empty input params.

+     */
+    @CalledByNative
+    public static String getMimeType(Context context, String uriString) {
+        ContentResolver resolver = context.getContentResolver();
+        Uri uri = Uri.parse(uriString);
+        if (resolver == null || uri == null) return "";
+        return resolver.getType(uri);

[nyquist, 2014/11/19 00:06:25]

Do we want to ensure that this never returns null?

[qinmin, 2014/11/19 02:13:07]

returned null for the empty inputs case

+    }
+
+    /**
      * Helper method to open a content URI and return the ParcelFileDescriptor.
      *
      * @param context {@link Context} in interest.
      * @param uriString the content URI to open.
      * @returns ParcelFileDescriptor of the content URI, or NULL if the file does not exist.
      */
     private static ParcelFileDescriptor getParcelFileDescriptor(Context context, String uriString) {
         ContentResolver resolver = context.getContentResolver();
         Uri uri = Uri.parse(uriString);
 
         ParcelFileDescriptor pfd = null;
         try {
             pfd = resolver.openFileDescriptor(uri, "r");
         } catch (java.io.FileNotFoundException e) {
             Log.w(TAG, "Cannot find content uri: " + uriString, e);
+        } catch (java.lang.SecurityException e) {

[nyquist, 2014/11/19 00:06:25]

Do you really need the 'java.lang.' prefix here?

[palmer, 2014/11/19 00:23:54]

Nope.

[qinmin, 2014/11/19 02:13:07]

removed

+            Log.w(TAG, "Cannot open content uri: " + uriString, e);
         }
         return pfd;
     }
 
     /**
      * Method to resolve the display name of a content URI.
      *
      * @param uri the content URI to be resolved.
      * @param contentResolver the content resolver to query.
      * @param columnField the column field to query.
@@ skipping 15 matching lines @@
         } catch (NullPointerException e) {
             // Some android models don't handle the provider call correctly.
             // see crbug.com/345393
             return "";
         } finally {
             if (cursor != null) cursor.close();
         }
         return "";
     }
 }