[Media Router] Add PresentationConnectionStateObserver and related APIs.

Introduce PresentationConnectionStateObserver class to listen for
connection state updates from MRPM.

Added related MR/MRPM APIs.

This is implemented as outlined in the proposal for reworking
connection state change listening.

Depends on crrev.com/1410143006

BUG=529893

Review URL: https://codereview.chromium.org/1414393009

Cr-Commit-Position: refs/heads/master@{#358855}

1 files changed, 36 insertions, 1 deletions

diff --git a/extensions/renderer/resources/media_router_bindings.js b/extensions/renderer/resources/media_router_bindings.js
index c877fd4..13bf88b 100644
--- a/extensions/renderer/resources/media_router_bindings.js
+++ b/extensions/renderer/resources/media_router_bindings.js
@@ -98,6 +98,28 @@ define('media_router_bindings', [
   }
 
   /**
+   * Converts presentation connection state to Mojo enum value.
+   * @param {!string} state
+   * @return {!mediaRouterMojom.MediaRouter.PresentationConnectionState}
+   */
+  function presentationConnectionStateToMojo_(state) {
+    switch (state) {
+      case 'connected':
+        return
+            mediaRouterMojom.MediaRouter.PresentationConnectionState.CONNECTED;
+      case 'closed':
+        return mediaRouterMojom.MediaRouter.PresentationConnectionState.CLOSED;
+      case 'terminated':
+        return
+            mediaRouterMojom.MediaRouter.PresentationConnectionState.TERMINATED;
+      default:
+        console.error('Unknown presentation connection state: ' + state);
+        return
+            mediaRouterMojom.MediaRouter.PresentationConnectionState.TERMINATED;
+    }
+  }
+
+  /**
    * Creates a new MediaRouter.
    * Converts a route struct to its Mojo form.
    * @param {!MediaRouterService} service
@@ -265,13 +287,26 @@ define('media_router_bindings', [
 
   /**
    * Called by the provider manager when sink availability has been updated.
-   * @param {!MediaRouter.SinkAvailability} The new sink availability.
+   * @param {!mediaRouterMojom.MediaRouter.SinkAvailability} availability
+   *     The new sink availability.
    */
   MediaRouter.prototype.onSinkAvailabilityUpdated = function(availability) {
     this.service_.onSinkAvailabilityUpdated(availability);
   };
 
   /**
+   * Called by the provider manager when the state of a presentation connected
+   * to a route has changed.
+   * @param {!string} routeId
+   * @param {!string} state
+   */
+  MediaRouter.prototype.onPresentationConnectionStateChanged =
+      function(routeId, state) {
+    this.service_.onPresentationConnectionStateChanged(
+        routeId, presentationConnectionStateToMojo_(state));
+  };
+
+  /**
    * Object containing callbacks set by the provider manager.
    *
    * @constructor