Allow Secure Stops to be queried and deleted by application ID

This CL changes the WVDrmPlugin so that an application can segregate
its secure stops from those of other applications by setting an
application ID.

This CL is a merge of the following Widevine CLs:
https://widevine-internal-review.googlesource.com/#/c/11565/
Add getSecureStop by ssid

https://widevine-internal-review.googlesource.com/#/c/11572
Add getSecureStop by SSID and releaseAllSecureStops by app id.

https://widevine-internal-review.googlesource.com/#/c/11564/
Store Usage Info by App Id (device_file stubs)

https://widevine-internal-review.googlesource.com/#/c/11563/
Add application id to StoreUsageInfo.

https://widevine-internal-review.googlesource.com/#/c/11561/
Added Application ID to PropertySet for secure stop.

bug: 18053197
bug: 18076411
Change-Id: I5444baf67ba1b960dee2dc958bced8de82ab70a3

libwvdrmengine/cdm/core/include/cdm_session.h

@@ -83,9 +83,11 @@ class CdmSession {
   virtual void OnTimerEvent(bool update_usage);
   virtual void OnKeyReleaseEvent(const CdmKeySetId& key_set_id);
 
+  virtual void GetApplicationId(std::string* app_id);
   virtual SecurityLevel GetRequestedSecurityLevel();
   virtual CdmSecurityLevel GetSecurityLevel();
 
+  virtual CdmResponseType DeleteUsageInformation(const std::string& app_id);
   virtual CdmResponseType UpdateUsageInformation();
 
   virtual bool is_initial_usage_update() { return is_initial_usage_update_; }
@@ -120,6 +122,7 @@ class CdmSession {
   bool is_offline_;
   bool is_release_;
   CdmSecurityLevel security_level_;
+  std::string app_id_;
 
   // decryption and usage flags
   bool is_initial_decryption_;