MediaRoute: Polish accessibility strings

Change-Id: Ic55df862fde38a2225f32561cb18fa7bf3a4c798
diff --git a/v7/mediarouter/res/values/strings.xml b/v7/mediarouter/res/values/strings.xml
index 789cf9a..88517ba 100644
--- a/v7/mediarouter/res/values/strings.xml
+++ b/v7/mediarouter/res/values/strings.xml
@@ -34,23 +34,23 @@
     <!-- Button to disconnect from a media route.  [CHAR LIMIT=30] -->
     <string name="mr_controller_disconnect">Disconnect</string>
 
-    <!-- Button to stop playback and disconnect from a media route.  [CHAR LIMIT=30] -->
+    <!-- Button to stop playback and disconnect from a media route. [CHAR LIMIT=30] -->
     <string name="mr_controller_stop">Stop casting</string>
 
-    <!-- Description for a button that closes the controller dialog -->
-    <string name="mr_controller_close_description">Close the controller dialog</string>
+    <!-- Accessibility description for the close button that closes the controller dialog. [CHAR LIMIT=NONE] -->
+    <string name="mr_controller_close_description">Close</string>
 
-    <!-- Accessibility description for the play button -->
+    <!-- Accessibility description for the play button that starts playback. [CHAR LIMIT=NONE] -->
     <string name="mr_controller_play">Play</string>
 
-    <!-- Accessibility description for the pause button -->
+    <!-- Accessibility description for the pause button that pauses playback. [CHAR LIMIT=NONE] -->
     <string name="mr_controller_pause">Pause</string>
 
-    <!-- Accessibility description for the collapse group button -->
-    <string name="mr_controller_collapse_group">Collapse group</string>
+    <!-- Accessibility description for the group expand button that shows group members of a selected route group. [CHAR LIMIT=NONE] -->
+    <string name="mr_controller_expand_group">Group expand</string>
 
-    <!-- Accessibility description for the expand group button -->
-    <string name="mr_controller_expand_group">Expand group</string>
+    <!-- Accessibility description for the group collapse button that hides group members of a selected group. [CHAR LIMIT=NONE] -->
+    <string name="mr_controller_collapse_group">Group collapse</string>
 
     <!-- Placeholder text to show when no title/description have been found for a given song/video. [CHAR LIMIT=50] -->
     <string name="mr_controller_no_info_available">No info available</string>