[eme] Check earlier for errors creating sessions.

In addition to checking earlier for errors creating sessions, don't try to
fulfil a promise twice.

BUG=826068
TEST=EME browser_tests pass

Change-Id: I912297ad3f8578660727638ead086eb28e90cc9c
Reviewed-on: https://chromium-review.googlesource.com/1006229Reviewed-by: Xiaohan Wang <xhwang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#550006}

media/blink/new_session_cdm_result_promise.cc

@@ -6,6 +6,7 @@
 
 #include "base/logging.h"
 #include "base/metrics/histogram_functions.h"
+#include "base/stl_util.h"
 #include "media/blink/cdm_result_promise_helper.h"
 #include "third_party/blink/public/platform/web_string.h"
 
@@ -52,11 +53,13 @@ NewSessionCdmResultPromise::NewSessionCdmResultPromise(
     const blink::WebContentDecryptionModuleResult& result,
     const std::string& key_system_uma_prefix,
     const std::string& uma_name,
-    const SessionInitializedCB& new_session_created_cb)
+    const SessionInitializedCB& new_session_created_cb,
+    const std::vector<SessionInitStatus>& expected_statuses)
     : web_cdm_result_(result),
       key_system_uma_prefix_(key_system_uma_prefix),
       uma_name_(uma_name),
       new_session_created_cb_(new_session_created_cb),
+      expected_statuses_(expected_statuses),
       creation_time_(base::TimeTicks::Now()) {}
 
 NewSessionCdmResultPromise::~NewSessionCdmResultPromise() {
@@ -70,7 +73,7 @@ void NewSessionCdmResultPromise::resolve(const std::string& session_id) {
   SessionInitStatus status = SessionInitStatus::UNKNOWN_STATUS;
   new_session_created_cb_.Run(session_id, &status);
 
-  if (status == SessionInitStatus::UNKNOWN_STATUS) {
+  if (!base::ContainsValue(expected_statuses_, status)) {
     reject(Exception::INVALID_STATE_ERROR, 0,
            "Cannot finish session initialization");
     return;

media/blink/new_session_cdm_result_promise.h

@@ -19,7 +19,7 @@
 namespace media {
 
 enum class SessionInitStatus {
-  // Error creating the session.
+  // Unable to determine the status.
   UNKNOWN_STATUS,
 
   // New session has been initialized.
@@ -39,7 +39,9 @@ typedef base::Callback<void(const std::string& session_id,
 // Special class for resolving a new session promise. Resolving a new session
 // promise returns the session ID (as a string), but the blink promise needs
 // to get passed a SessionStatus. This class converts the session id to a
-// SessionStatus by calling |new_session_created_cb|.
+// SessionStatus by calling |new_session_created_cb|. The value returned by
+// |new_session_created_cb| must be in |expected_statuses| for the promise to
+// be resolved. If it's not in the list, the promise will be rejected.
 class MEDIA_BLINK_EXPORT NewSessionCdmResultPromise
     : public CdmPromiseTemplate<std::string> {
  public:
@@ -47,7 +49,8 @@ class MEDIA_BLINK_EXPORT NewSessionCdmResultPromise
       const blink::WebContentDecryptionModuleResult& result,
       const std::string& key_system_uma_prefix,
       const std::string& uma_name,
-      const SessionInitializedCB& new_session_created_cb);
+      const SessionInitializedCB& new_session_created_cb,
+      const std::vector<SessionInitStatus>& expected_statuses);
   ~NewSessionCdmResultPromise() override;
 
   // CdmPromiseTemplate<T> implementation.
@@ -64,8 +67,10 @@ class MEDIA_BLINK_EXPORT NewSessionCdmResultPromise
   std::string uma_name_;
 
   // Called on resolve() to convert the session ID into a SessionInitStatus to
-  // be reported to blink.
+  // be reported to blink. Returned status must be in |expected_statuses_| or
+  // else the promise will be rejected.
   SessionInitializedCB new_session_created_cb_;
+  std::vector<SessionInitStatus> expected_statuses_;
 
   // Time when |this| is created.
   base::TimeTicks creation_time_;

media/blink/webcontentdecryptionmodulesession_impl.cc

@@ -349,7 +349,8 @@ void WebContentDecryptionModuleSessionImpl::InitializeNewSession(
           result, adapter_->GetKeySystemUMAPrefix(), kGenerateRequestUMAName,
           base::Bind(
               &WebContentDecryptionModuleSessionImpl::OnSessionInitialized,
-              weak_ptr_factory_.GetWeakPtr()))));
+              weak_ptr_factory_.GetWeakPtr()),
+          {SessionInitStatus::NEW_SESSION})));
 }
 
 void WebContentDecryptionModuleSessionImpl::Load(
@@ -384,7 +385,9 @@ void WebContentDecryptionModuleSessionImpl::Load(
           result, adapter_->GetKeySystemUMAPrefix(), kLoadSessionUMAName,
           base::Bind(
               &WebContentDecryptionModuleSessionImpl::OnSessionInitialized,
-              weak_ptr_factory_.GetWeakPtr()))));
+              weak_ptr_factory_.GetWeakPtr()),
+          {SessionInitStatus::NEW_SESSION,
+           SessionInitStatus::SESSION_NOT_FOUND})));
 }
 
 void WebContentDecryptionModuleSessionImpl::Update(

third_party/blink/renderer/modules/encryptedmedia/media_key_session.cc

@@ -238,11 +238,7 @@ class NewSessionResultPromise : public ContentDecryptionModuleResultPromise {
     if (!IsValidToFulfillPromise())
       return;
 
-    if (status != WebContentDecryptionModuleResult::kNewSession) {
-      NOTREACHED();
-      Reject(kInvalidStateError, "Unexpected completion.");
-    }
-
+    DCHECK_EQ(status, WebContentDecryptionModuleResult::kNewSession);
     session_->FinishGenerateRequest();
     Resolve();
   }
@@ -274,23 +270,14 @@ class LoadSessionResultPromise : public ContentDecryptionModuleResultPromise {
     if (!IsValidToFulfillPromise())
       return;
 
-    switch (status) {
-      case WebContentDecryptionModuleResult::kNewSession:
-        session_->FinishLoad();
-        Resolve(true);
-        return;
-
-      case WebContentDecryptionModuleResult::kSessionNotFound:
-        Resolve(false);
-        return;
-
-      case WebContentDecryptionModuleResult::kSessionAlreadyExists:
-        NOTREACHED();
-        Reject(kInvalidStateError, "Unexpected completion.");
-        return;
+    if (status == WebContentDecryptionModuleResult::kSessionNotFound) {
+      Resolve(false);
+      return;
     }
 
-    NOTREACHED();
+    DCHECK_EQ(status, WebContentDecryptionModuleResult::kNewSession);
+    session_->FinishLoad();
+    Resolve(true);
   }
 
   void Trace(blink::Visitor* visitor) override {