Implement "Key Presence" step in "Encrypted Block Encounted" algorithm in EME.

webkit/media/crypto/proxy_decryptor.cc

Index: webkit/media/crypto/proxy_decryptor.cc
diff --git a/webkit/media/crypto/proxy_decryptor.cc b/webkit/media/crypto/proxy_decryptor.cc
index 0b786552b577ea199d042517195a2a20ffb05cb1..8dd320fd3be649ae14570cc3c75b4645a5aa789a 100644
--- a/webkit/media/crypto/proxy_decryptor.cc
+++ b/webkit/media/crypto/proxy_decryptor.cc
@@ -4,7 +4,12 @@
 
 #include "webkit/media/crypto/proxy_decryptor.h"
 
+#include <algorithm>
+
+#include "base/bind.h"
+#include "base/location.h"
 #include "base/logging.h"
+#include "base/message_loop_proxy.h"
 #include "media/base/decoder_buffer.h"
 #include "media/base/decryptor_client.h"
 #include "media/crypto/aes_decryptor.h"
@@ -41,6 +46,19 @@ static scoped_refptr<webkit::ppapi::PluginInstance> CreatePluginInstance(
   return ppapi_plugin->instance();
 }
 
+// TODO(xhwang): Simplify this function. This is mostly caused by the fact that
+// we need to copy a scoped_array<uint8>.
+static void FireNeedKey(media::DecryptorClient* client,
+                        const scoped_refptr<media::DecoderBuffer>& encrypted) {
+  DCHECK(client);
+  DCHECK(encrypted);
+  DCHECK(encrypted->GetDecryptConfig());
+  std::string key_id = encrypted->GetDecryptConfig()->key_id();
+  scoped_array<uint8> key_id_array(new uint8[key_id.size()]);
+  memcpy(key_id_array.get(), key_id.data(), key_id.size());
+  client->NeedKey("", "", key_id_array.Pass(), key_id.size());
+}
+
 ProxyDecryptor::ProxyDecryptor(
     media::DecryptorClient* decryptor_client,
     WebKit::WebMediaPlayerClient* web_media_player_client,
@@ -58,12 +76,12 @@ void ProxyDecryptor::GenerateKeyRequest(const std::string& key_system,
                                         int init_data_length) {
   // We do not support run-time switching of decryptors. GenerateKeyRequest()
   // only creates a new decryptor when |decryptor_| is not initialized.
+  DVLOG(1) << "GenerateKeyRequest: key_system = " << key_system;
   if (!decryptor_.get()) {
     base::AutoLock auto_lock(lock_);
     decryptor_ = CreateDecryptor(key_system);
   }
 
-  DCHECK(client_);
   if (!decryptor_.get()) {
     client_->KeyError(key_system, "", media::Decryptor::kUnknownError, 0);
     return;
@@ -78,14 +96,32 @@ void ProxyDecryptor::AddKey(const std::string& key_system,
                             const uint8* init_data,
                             int init_data_length,
                             const std::string& session_id) {
+  DVLOG(1) << "AddKey()";
+
   // WebMediaPlayerImpl ensures GenerateKeyRequest() has been called.
   DCHECK(decryptor_.get());
   decryptor_->AddKey(key_system, key, key_length, init_data, init_data_length,
                      session_id);
+
+  std::vector<base::Closure> closures_to_run;
+  {
+    base::AutoLock auto_lock(lock_);
+    std::swap(pending_decrypt_closures_, closures_to_run);
+  }
+
+  // Fire all pending callbacks here because only the |decryptor_| knows if the
+  // pending buffers can be decrypted or not.
+  for (std::vector<base::Closure>::iterator iter = closures_to_run.begin();
+       iter != closures_to_run.end();
+       ++iter) {
+    iter->Run();
+  }
 }
 
 void ProxyDecryptor::CancelKeyRequest(const std::string& key_system,
                                       const std::string& session_id) {
+  DVLOG(1) << "CancelKeyRequest()";
+
   // WebMediaPlayerImpl ensures GenerateKeyRequest() has been called.
   DCHECK(decryptor_.get());
   decryptor_->CancelKeyRequest(key_system, session_id);
@@ -99,14 +135,24 @@ void ProxyDecryptor::Decrypt(
   {
     base::AutoLock auto_lock(lock_);
     decryptor = decryptor_.get();
-  }
-  if (!decryptor) {
-    DVLOG(1) << "ProxyDecryptor::Decrypt(): decryptor not initialized.";
-    decrypt_cb.Run(kError, NULL);
-    return;
+    if (!decryptor) {
+      DVLOG(1) << "ProxyDecryptor::Decrypt(): decryptor not initialized.";
+      pending_decrypt_closures_.push_back(
+          base::Bind(&ProxyDecryptor::DecryptOnMessageLoop,
+                     base::Unretained(this),
+                     base::MessageLoopProxy::current(), encrypted,
+                     decrypt_cb));
+      // TODO(xhwang): The same NeedKey may be fired here and multiple times in
+      // OnBufferDecrypted(). While the spec says only one NeedKey should be
+      // fired. Leave them as is since the spec about this may change.
+      FireNeedKey(client_, encrypted);
+      return;
+    }
   }
 
-  decryptor->Decrypt(encrypted, decrypt_cb);
+  decryptor->Decrypt(encrypted, base::Bind(
+      &ProxyDecryptor::OnBufferDecrypted, base::Unretained(this),
+      base::MessageLoopProxy::current(), encrypted, decrypt_cb));
 }
 
 scoped_ptr<media::Decryptor> ProxyDecryptor::CreatePpapiDecryptor(
@@ -141,4 +187,47 @@ scoped_ptr<media::Decryptor> ProxyDecryptor::CreateDecryptor(
   return CreatePpapiDecryptor(key_system);
 }
 
+void ProxyDecryptor::DecryptOnMessageLoop(
+    const scoped_refptr<base::MessageLoopProxy>& message_loop_proxy,
+    const scoped_refptr<media::DecoderBuffer>& encrypted,
+    const media::Decryptor::DecryptCB& decrypt_cb) {
+  DCHECK(decryptor_.get());
+
+  if (!message_loop_proxy->BelongsToCurrentThread()) {
+    message_loop_proxy->PostTask(FROM_HERE, base::Bind(
+        &ProxyDecryptor::DecryptOnMessageLoop, base::Unretained(this),
+        message_loop_proxy, encrypted, decrypt_cb));
+    return;
+  }
+
+  decryptor_->Decrypt(encrypted, base::Bind(&ProxyDecryptor::OnBufferDecrypted,
+      base::Unretained(this), message_loop_proxy, encrypted, decrypt_cb));
+}
+
+void ProxyDecryptor::OnBufferDecrypted(
+    const scoped_refptr<base::MessageLoopProxy>& message_loop_proxy,
+    const scoped_refptr<media::DecoderBuffer>& encrypted,
+    const media::Decryptor::DecryptCB& decrypt_cb,
+    media::Decryptor::DecryptStatus status,
+    const scoped_refptr<media::DecoderBuffer>& decrypted) {
+  if (status == media::Decryptor::kSuccess ||
+      status == media::Decryptor::kError) {
+    decrypt_cb.Run(status, decrypted);
+    return;
+  }
+
+  DCHECK_EQ(status, media::Decryptor::kNoKey);
+  DVLOG(1) << "OnBufferDecrypted(): kNoKey fired";
+  {
+    base::AutoLock auto_lock(lock_);
+    pending_decrypt_closures_.push_back(base::Bind(
+        &ProxyDecryptor::DecryptOnMessageLoop, base::Unretained(this),
+        message_loop_proxy, encrypted, decrypt_cb));
+  }
+  // TODO(xhwang): The same NeedKey may be fired multiple times here and also
+  // in Decrypt(). While the spec says only one NeedKey should be fired. Leave
+  // them as is since the spec about this may change.
+  FireNeedKey(client_, encrypted);
+}
+
 }  // namespace webkit_media