WebShare: Log the type of rejected files

Web Share has an accept list for MIME types and file extensions.

When a file share attempt fails because a file has a MIME type or
extension not an accept list, we now log an error.

BUG=965461

Change-Id: Ic860ba6842c5fe1cf09bad3de9a4f3e99ce304e2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1623656
Auto-Submit: Eric Willigers <ericwilligers@chromium.org>
Reviewed-by: Ted Choc <tedchoc@chromium.org>
Reviewed-by: Raymes Khoury <raymes@chromium.org>
Commit-Queue: Eric Willigers <ericwilligers@chromium.org>
Cr-Commit-Position: refs/heads/master@{#662838}

chrome/android/java/src/org/chromium/chrome/browser/webshare/ShareServiceImpl.java

@@ -200,6 +200,9 @@ public class ShareServiceImpl implements ShareService {
 
         for (SharedFile file : files) {
             if (isDangerousFilename(file.name) || isDangerousMimeType(file.blob.contentType)) {
+                Log.i(TAG,
+                        "Cannot share potentially dangerous \"" + file.blob.contentType
+                                + "\" file \"" + file.name + "\".");
                 callback.call(ShareError.PERMISSION_DENIED);
                 return;
             }