Fixes for query information and usage reporting

* The Usage APIs return usage reports from either L1 or L3 (if available).
* Correction to when usage reports are saved. In addition to other events
  they are now saved when keys are loaded, usage reports are released and soon
  after first decryption and periodically (60 seconds) after that,
  if decryption takes place.
* Usage reports now get deleted on an unprovision request.
* Policy timer is now started when offline licenses are restored.
* Usage session is now released, when a usage response is received.
* Usage tests ahev been enabled.
* Added CDM extended duration (integration) tests to test usage reporting
  and querying. These need to be run manually as they take a while (currently
  half an hour).

b/15592374

[ Merge of https://widevine-internal-review.googlesource.com/#/c/10800
  from the Widevine CDM repo ]

Change-Id: Ia817e03ebbe880e08ba7b4a235ecb82b3ff35fbf

libwvdrmengine/cdm/core/include/crypto_session.h

@@ -84,6 +84,7 @@ class CryptoSession {
   // Media data path
   virtual CdmResponseType Decrypt(const CdmDecryptionParameters& parameters);
 
+  // Usage related methods
   virtual bool UsageInformationSupport(bool* has_support);
   virtual CdmResponseType UpdateUsageInformation();
   virtual CdmResponseType DeactivateUsageInformation(
@@ -95,6 +96,7 @@ class CryptoSession {
   virtual CdmResponseType ReleaseUsageInformation(
       const std::string& message, const std::string& signature,
       const std::string& provider_session_token);
+  virtual CdmResponseType DeleteAllUsageReports();
 
   virtual bool GetHdcpCapabilities(OemCryptoHdcpVersion* current,
                                    OemCryptoHdcpVersion* max);