Fix resource leaks in CDM implementation.

ppapi/proxy/ppp_content_decryptor_private_proxy.cc

Index: ppapi/proxy/ppp_content_decryptor_private_proxy.cc
diff --git a/ppapi/proxy/ppp_content_decryptor_private_proxy.cc b/ppapi/proxy/ppp_content_decryptor_private_proxy.cc
index fe6a928a64f753b7242e40971a832670f0c2bb56..cad8df064be265b61a6be305feb3a04e2ac35a55 100644
--- a/ppapi/proxy/ppp_content_decryptor_private_proxy.cc
+++ b/ppapi/proxy/ppp_content_decryptor_private_proxy.cc
@@ -75,6 +75,22 @@ PP_Var ExtractReceivedVarAndAddRef(Dispatcher* dispatcher,
   return var;
 }
 
+// Increments the reference count on |resource| to ensure that it remains valid
+// until the plugin receives the resource within the asynchronous message sent
+// from the proxy.  The plugin side takes ownership of that reference. Returns
+// PP_TRUE when the reference is successfully added, PP_FALSE otherwise.
+PP_Bool AddRefResourceForPlugin(HostDispatcher* dispatcher,
+                                PP_Resource resource) {
+  const PPB_Core* core = static_cast<const PPB_Core*>(
+      dispatcher->local_get_interface()(PPB_CORE_INTERFACE));
+  if (!core) {
+    NOTREACHED();
+    return PP_FALSE;
+  }
+  core->AddRefResource(resource);
+  return PP_TRUE;
+}
+
 PP_Bool GenerateKeyRequest(PP_Instance instance,
                            PP_Var key_system,
                            PP_Var init_data) {
@@ -133,18 +149,12 @@ PP_Bool Decrypt(PP_Instance instance,
     NOTREACHED();
     return PP_FALSE;
   }
-  const PPB_Core* core = static_cast<const PPB_Core*>(
-      dispatcher->local_get_interface()(PPB_CORE_INTERFACE));
-  if (!core) {
+
+  if (AddRefResourceForPlugin(dispatcher, encrypted_block) != PP_TRUE) {

[dmichael (off chromium), 2012/09/05 19:46:19]

You could just do if (!AddRefResource...) {
right?

[Tom Finegan, 2012/09/05 20:15:26]

Done.

     NOTREACHED();
     return PP_FALSE;
   }
 
-  // We need to take a ref on the resource now. The browser may drop
-  // references once we return from here, but we're sending an asynchronous
-  // message. The plugin side takes ownership of that reference.
-  core->AddRefResource(encrypted_block);
-
   HostResource host_resource;
   host_resource.SetHostResource(instance, encrypted_block);
 
@@ -184,6 +194,11 @@ PP_Bool DecryptAndDecode(PP_Instance instance,
     return PP_FALSE;
   }
 
+  if (AddRefResourceForPlugin(dispatcher, encrypted_block) != PP_TRUE) {
+    NOTREACHED();
+    return PP_FALSE;
+  }
+
   HostResource host_resource;
   host_resource.SetHostResource(instance, encrypted_block);
 
@@ -321,6 +336,11 @@ void PPP_ContentDecryptor_Private_Proxy::OnMsgDecrypt(
                       plugin_resource,
                       const_cast<const PP_EncryptedBlockInfo*>(&block_info));
   }
+
+  // Tell the host to release its reference on the resource. The plugin has
+  // taken ownership.
+  dispatcher()->Send(new PpapiHostMsg_PPBCore_ReleaseResource(
+      API_ID_PPB_CORE, encrypted_buffer.resource));
 }
 
 void PPP_ContentDecryptor_Private_Proxy::OnMsgDecryptAndDecode(
@@ -340,6 +360,11 @@ void PPP_ContentDecryptor_Private_Proxy::OnMsgDecryptAndDecode(
                       plugin_resource,
                       const_cast<const PP_EncryptedBlockInfo*>(&block_info));
   }
+
+  // Tell the host to release its reference on the resource. The plugin has
+  // taken ownership.
+  dispatcher()->Send(new PpapiHostMsg_PPBCore_ReleaseResource(
+      API_ID_PPB_CORE, encrypted_buffer.resource));

[dmichael (off chromium), 2012/09/05 19:46:19]

Sorry, as I mentioned in a more recent comment, I was wrong about this part. The
plugin assumes it gets 1 ref count, and it will release it later when the
plugin-side refcount goes to 0. (same in Decrypt())

[Tom Finegan, 2012/09/05 20:15:26]

Removed.

 }
 
 }  // namespace proxy