Rework V1.2 ContextHub HAL spec

In the final implementation that makes use of this HAL version,
ContextHubMsg's don't have permissions information when they are sent
from the framework to the HAL since the framework is the end decider for
whether its clients have the right permissions.

Bug: 180606685
Test: presubmits
Change-Id: I385edce48ff71abc1c684919532b6c578df2a414

contexthub/1.2/IContexthub.hal

@@ -50,18 +50,6 @@ interface IContexthub extends @1.1::IContexthub {
      */
     registerCallback_1_2(uint32_t hubId, IContexthubCallback cb) generates (Result result);
 
-    /**
-     * Send a message to a hub
-     *
-     * @param hubId identifier for hub to send message to
-     * @param msg   message to be sent
-     *
-     * @return result OK if successful, error code otherwise
-     *                BAD_VALUE if parameters are not valid
-     *                TRANSACTION_FAILED if message send failed
-     */
-    sendMessageToHub_1_2(uint32_t hubId, ContextHubMsg msg) generates (Result result);
-
     /**
      * Notification sent by the framework to indicate that the user
      * has changed a setting.

contexthub/1.2/types.hal

@@ -45,11 +45,8 @@ struct ContextHubMsg {
     @1.0::ContextHubMsg msg_1_0;
 
     /**
-     * The list of Android permissions that the sender of this message has at
-     * the time the message was sent.
-     *
-     * The HAL MUST drop messages to nanoapps if this list of permissions is not
-     * a superset of those of the receiving nanoapp(s).
+     * The list of Android permissions held by the sending nanoapp at the time
+     * the message was sent.
      *
      * The framework MUST drop messages to host apps that don't have a superset
      * of the permissions that the sending nanoapp is using.