Support video attachments through GalleryMediaChooser

GalleryMediaChooser supports video types and more image types also. And
video thumbnails are overlaid with the play button image to distinguish
between images and videos.

Note:
 1. EXTRA_ALLOW_MULTIPLE is not specified for ACTION_GET_CONTENT.
 2. Files, methods and variables' name are still including "image".
 3. Content descriptions are not updated.

Test: Manual

Change-Id: I961928f150e4ae8ee80a1fba2f20c37fb5426669
Signed-off-by: Taesu Lee <taesu82.lee@samsung.com>

src/com/android/messaging/ui/UIIntents.java

@@ -44,8 +44,8 @@ public abstract class UIIntents {
     // Sending draft data (from share intent / message forwarding) to the ConversationActivity.
     public static final String UI_INTENT_EXTRA_DRAFT_DATA = "draft_data";
 
-    // The request code for picking image from the Document picker.
-    public static final int REQUEST_PICK_IMAGE_FROM_DOCUMENT_PICKER = 1400;
+    // The request code for picking a media from the Document picker.
+    public static final int REQUEST_PICK_MEDIA_FROM_DOCUMENT_PICKER = 1400;
 
     // Indicates what type of notification this applies to (See BugleNotifications:
     // UPDATE_NONE, UPDATE_MESSAGES, UPDATE_ERRORS, UPDATE_ALL)
@@ -166,7 +166,8 @@ public abstract class UIIntents {
     public abstract void launchAddContactActivity(final Context context, final String destination);
 
     /**
-     * Launch an activity to show the document picker to pick an image.
+     * Launch an activity to show the document picker to pick an image/video.
+     *
      * @param fragment the requesting fragment
      */
     public abstract void launchDocumentImagePicker(final Fragment fragment);