Extract getMediaViewerIntent logic from DownloadUtils into MediaUtils

This CL creates a new MediaViewerUtils class and adds the logic for
creating a media-viewing CustomTabActivity Intent, removing it from
DownloadUtils. This will make sharing that logic with the upcoming
MediaViewerActivity cleaner.

Bug: 778276
Change-Id: Ie967e5600943558e08c26492e38831e6da7c153d
Reviewed-on: https://chromium-review.googlesource.com/821515
Reviewed-by: Mounir Lamouri <[email protected]>
Reviewed-by: David Trainor <[email protected]>
Commit-Queue: Tommy Steimel <[email protected]>
Cr-Commit-Position: refs/heads/master@{#525092}
diff --git a/chrome/android/java_sources.gni b/chrome/android/java_sources.gni
index 4891e18..3f129b7 100644
--- a/chrome/android/java_sources.gni
+++ b/chrome/android/java_sources.gni
@@ -570,6 +570,7 @@
   "java/src/org/chromium/chrome/browser/locale/SogouPromoDialog.java",
   "java/src/org/chromium/chrome/browser/locale/SpecialLocaleHandler.java",
   "java/src/org/chromium/chrome/browser/media/MediaCaptureNotificationService.java",
+  "java/src/org/chromium/chrome/browser/media/MediaViewerUtils.java",
   "java/src/org/chromium/chrome/browser/media/PictureInPictureController.java",
   "java/src/org/chromium/chrome/browser/media/cdm/MediaDrmCredentialManager.java",
   "java/src/org/chromium/chrome/browser/media/remote/AbstractMediaRouteController.java",