Grant delete on Entry from webrtcLoggingPrivate.getLogsDirectory

This API is intended for use by an app to read "WebRTC Logs" files
generated for debug purposes on devices within Google. I initially
proposed making it purely read-only to prevent contention with
the creation and writing to audio debug files; however, the app
can restrict itself to acting on files that the aec dump process
has finished with (as indicated by getting a callback from
startAudioDebugRecordings/stopAudioDebugRecordings).

While a low volume of debug recordings would eventually be cleaned up
after 5 days and a reboot (per
WebRtcLogUtil::DeleteOldWebRtcLogFilesForAllProfiles), the needed
frequency and volume of recordings would be more flexible if the
app could clean up files it generated.

Bug: 775961
Change-Id: I8492b0619ee1c98737f0248190d68a1e3bee5bca
Reviewed-on: https://chromium-review.googlesource.com/795671Reviewed-by: Mustafa Emre Acer <meacer@chromium.org>
Reviewed-by: Tommi <tommi@chromium.org>
Commit-Queue: Adrian Elder <aelder@chromium.org>
Cr-Commit-Position: refs/heads/master@{#520176}

chrome/browser/media/webrtc/webrtc_logging_handler_host.cc

@@ -303,11 +303,13 @@ void WebRtcLoggingHandlerHost::GrantLogsDirectoryAccess(
       storage::kFileSystemTypeNativeLocal, std::string(), logs_path,
       &registered_name);
 
-  // Only granting read-only access to reduce contention with webrtcLogging APIs
-  // that modify files in that folder.
+  // Only granting read and delete access to reduce contention with
+  // webrtcLogging APIs that modify files in that folder.
   content::ChildProcessSecurityPolicy* policy =
       content::ChildProcessSecurityPolicy::GetInstance();
   policy->GrantReadFileSystem(render_process_id_, filesystem_id);
+  // Delete is needed to prevent accumulation of files.
+  policy->GrantDeleteFromFileSystem(render_process_id_, filesystem_id);
   BrowserThread::PostTask(
       BrowserThread::UI, FROM_HERE,
       base::BindOnce(callback, filesystem_id, registered_name));

chrome/test/data/extensions/api_test/webrtc_logging_private/get_logs_directory/test.js

@@ -71,6 +71,22 @@ function testCanReadFile() {
   });
 }
 
+function testCanRemoveFile() {
+  chrome.webrtcLoggingPrivate.getLogsDirectory(function(directoryEntry) {
+    readFileEntries(directoryEntry, function(entries) {
+      chrome.test.assertEq(1, entries.length);
+      var fileEntry = entries[0];
+      chrome.test.assertTrue(fileEntry.isFile);
+      fileEntry.remove(function() {
+        readFileEntries(directoryEntry, function(entries) {
+          chrome.test.assertEq(0, entries.length);
+          chrome.test.succeed();
+        });
+      });
+    });
+  });
+}
+
 function testCannotWriteToFile() {
   chrome.webrtcLoggingPrivate.getLogsDirectory(function(directoryEntry) {
     readFileEntries(directoryEntry, function(entries) {
@@ -93,10 +109,15 @@ function testCannotWriteToFile() {
 
 var testGroups = {
   'test_without_directory': [
-    testGetsReadOnlyDirectoryEntry, testEmptyDirectory,
+    testGetsReadOnlyDirectoryEntry,
+    testEmptyDirectory,
   ],
   'test_with_file_in_directory': [
-    testGetsReadOnlyDirectoryEntry, testCanReadFile, testCannotWriteToFile,
+    testGetsReadOnlyDirectoryEntry,
+    testCanReadFile,
+    testCannotWriteToFile,
+    // Must be run last, since it deletes the test file.
+    testCanRemoveFile,
   ],
 };