[MediaRouter] Renames CloseRoute() to Terminate() and creates DetachRoute()

chrome/browser/media/router/media_router_metrics.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_MEDIA_ROUTER_MEDIA_ROUTER_METRICS_H_
 #define CHROME_BROWSER_MEDIA_ROUTER_MEDIA_ROUTER_METRICS_H_
 
 namespace media_router {
 
 // NOTE: Do not renumber enums as that would confuse interpretation of
 // previously logged data. When making changes, also update the enum list
 // in tools/metrics/histograms/histograms.xml to keep it in sync.
 
 // Where the user clicked to open the Media Router dialog.
 enum class MediaRouterDialogOpenOrigin {
   TOOLBAR = 0,
   OVERFLOW_MENU = 1,
   CONTEXTUAL_MENU = 2,
   PAGE = 3,
 
   // NOTE: Add entries only immediately above this line.
   TOTAL_COUNT = 4
 };
 
 // Why the Media Route Provider process was woken up.
 enum class MediaRouteProviderWakeReason {
   CREATE_ROUTE = 0,
   JOIN_ROUTE = 1,
-  CLOSE_ROUTE = 2,
+  TERMINATE_ROUTE = 2,
   SEND_SESSION_MESSAGE = 3,
   SEND_SESSION_BINARY_MESSAGE = 4,
-  PRESENTATION_SESSION_DETACHED = 5,
+  DETACH_ROUTE = 5,

[mlamouri (slow - plz ping), 2015/12/10 15:39:51]

open question: would there be a benefit in trying to differentiate detached
route because of close() and detached route because of GC? (note: Blink keeps
track of calls to close() so that might not be a big deal)

[mark a. foltz, 2015/12/10 23:46:48]

I think for now we should be able to get a good estimate based on the difference
between this histogram and the usecounter.  If we want to be precise we could
plumb through a DetachReason from Blink.

   START_OBSERVING_MEDIA_SINKS = 6,
   STOP_OBSERVING_MEDIA_SINKS = 7,
   START_OBSERVING_MEDIA_ROUTES = 8,
   STOP_OBSERVING_MEDIA_ROUTES = 9,
   LISTEN_FOR_ROUTE_MESSAGES = 10,
   STOP_LISTENING_FOR_ROUTE_MESSAGES = 11,
   CONNECTION_ERROR = 12,
   REGISTER_MEDIA_ROUTE_PROVIDER = 13,
 
   // NOTE: Add entries only immediately above this line.
   TOTAL_COUNT = 14
 };
 
 class MediaRouterMetrics {
  public:
   // Records where the user clicked to open the Media Router dialog.
   static void RecordMediaRouterDialogOrigin(
       MediaRouterDialogOpenOrigin origin);
 
   // Records why the media route provider extension was woken up.
   static void RecordMediaRouteProviderWakeReason(
       MediaRouteProviderWakeReason reason);
 };
 
 }  // namespace media_router
 
 #endif  // CHROME_BROWSER_MEDIA_ROUTER_MEDIA_ROUTER_METRICS_H_