[Fuchsia] Move CDM data file i/o off main thread

The FuchsiaCdmManager needs to create directories for each origin to
pass to the platform CDM services to fulfill EME origin isolation
requirements. The FuchsiaCdmManager runs on the main thread and the
calls to CreateDirectoryAndGetError are potentially blocking. This CL
moves the directory creation step to a background task.

Bug: 1140655
Change-Id: I060edc909976e7b5a493afc3bc9a2a26e26994be
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2500532Reviewed-by: Wez <wez@chromium.org>
Commit-Queue: RJ Ascani <rjascani@google.com>
Cr-Commit-Position: refs/heads/master@{#821353}

media/fuchsia/cdm/service/fuchsia_cdm_manager.cc

@@ -17,7 +17,10 @@
 #include "base/fuchsia/fuchsia_logging.h"
 #include "base/hash/hash.h"
 #include "base/logging.h"
+#include "base/optional.h"
 #include "base/strings/string_number_conversions.h"
+#include "base/task/task_traits.h"
+#include "base/task/thread_pool.h"
 #include "media/fuchsia/cdm/service/provisioning_fetcher_impl.h"
 #include "url/origin.h"
 
@@ -30,6 +33,16 @@ std::string HexEncodeHash(const std::string& name) {
   return base::HexEncode(&hash, sizeof(uint32_t));
 }
 
+// Returns a nullopt if storage was created successfully.
+base::Optional<base::File::Error> CreateStorageDirectory(base::FilePath path) {
+  base::File::Error error;
+  bool success = base::CreateDirectoryAndGetError(path, &error);
+  if (!success) {
+    return error;
+  }
+  return {};
+}
+
 }  // namespace
 
 // Manages individual KeySystem connections. Provides data stores and
@@ -174,24 +187,14 @@ void FuchsiaCdmManager::CreateAndProvision(
         request) {
   DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
 
-  KeySystemClient* key_system_client = GetOrCreateKeySystemClient(key_system);
-  if (!key_system_client) {
-    // GetOrCreateKeySystemClient will log the reason for failure.
-    return;
-  }
-
   base::FilePath storage_path = GetStoragePath(key_system, origin);
-  base::File::Error error;
-  bool success = base::CreateDirectoryAndGetError(storage_path, &error);
-  if (!success) {
-    DLOG(ERROR) << "Failed to create directory: " << storage_path
-                << ", error: " << error;
-    return;
-  }
 
-  key_system_client->CreateCdm(std::move(storage_path),
-                               std::move(create_fetcher_cb),
-                               std::move(request));
+  base::ThreadPool::PostTaskAndReplyWithResult(
+      FROM_HERE, {base::MayBlock()},
+      base::BindOnce(&CreateStorageDirectory, storage_path),
+      base::BindOnce(&FuchsiaCdmManager::CreateCdm, weak_factory_.GetWeakPtr(),
+                     key_system, std::move(create_fetcher_cb),
+                     std::move(request), storage_path));
 }
 
 void FuchsiaCdmManager::set_on_key_system_disconnect_for_test_callback(
@@ -241,6 +244,35 @@ base::FilePath FuchsiaCdmManager::GetStoragePath(const std::string& key_system,
       .Append(HexEncodeHash(key_system));
 }
 
+void FuchsiaCdmManager::CreateCdm(
+    const std::string& key_system_name,
+    CreateFetcherCB create_fetcher_cb,
+    fidl::InterfaceRequest<fuchsia::media::drm::ContentDecryptionModule>
+        request,
+    base::FilePath storage_path,
+    base::Optional<base::File::Error> storage_creation_error) {
+  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
+
+  if (storage_creation_error) {
+    DLOG(ERROR) << "Failed to create directory: " << storage_path
+                << ", error: " << *storage_creation_error;
+    request.Close(ZX_ERR_NO_RESOURCES);
+    return;
+  }
+
+  KeySystemClient* key_system_client =
+      GetOrCreateKeySystemClient(key_system_name);
+  if (!key_system_client) {
+    // GetOrCreateKeySystemClient will log the reason for failure.
+    request.Close(ZX_ERR_NOT_FOUND);
+    return;
+  }
+
+  key_system_client->CreateCdm(std::move(storage_path),
+                               std::move(create_fetcher_cb),
+                               std::move(request));
+}
+
 void FuchsiaCdmManager::OnKeySystemClientError(
     const std::string& key_system_name) {
   if (on_key_system_disconnect_for_test_callback_) {

media/fuchsia/cdm/service/fuchsia_cdm_manager.h

@@ -10,8 +10,11 @@
 
 #include "base/callback_forward.h"
 #include "base/containers/flat_map.h"
+#include "base/files/file.h"
 #include "base/files/file_path.h"
 #include "base/macros.h"
+#include "base/memory/weak_ptr.h"
+#include "base/optional.h"
 #include "base/threading/thread_checker.h"
 #include "media/base/provision_fetcher.h"
 
@@ -63,6 +66,13 @@ class FuchsiaCdmManager {
   KeySystemClient* CreateKeySystemClient(const std::string& key_system_name);
   base::FilePath GetStoragePath(const std::string& key_system_name,
                                 const url::Origin& origin);
+  void CreateCdm(
+      const std::string& key_system_name,
+      CreateFetcherCB create_fetcher_cb,
+      fidl::InterfaceRequest<fuchsia::media::drm::ContentDecryptionModule>
+          request,
+      base::FilePath storage_path,
+      base::Optional<base::File::Error> storage_creation_error);
   void OnKeySystemClientError(const std::string& key_system_name);
 
   // A map of callbacks to create KeySystem channels indexed by their EME name.
@@ -79,6 +89,7 @@ class FuchsiaCdmManager {
       on_key_system_disconnect_for_test_callback_;
 
   THREAD_CHECKER(thread_checker_);
+  base::WeakPtrFactory<FuchsiaCdmManager> weak_factory_{this};
 };
 
 }  // namespace media

media/fuchsia/cdm/service/fuchsia_cdm_manager_test.cc

@@ -96,8 +96,8 @@ class FuchsiaCdmManagerTest : public ::testing::Test {
     return mock_key_systems_[key_system_name];
   }
 
-  base::test::SingleThreadTaskEnvironment task_environment_{
-      base::test::SingleThreadTaskEnvironment::MainThreadType::IO};
+  base::test::TaskEnvironment task_environment_{
+      base::test::TaskEnvironment::MainThreadType::IO};
 
   MockKeySystemMap mock_key_systems_;
   base::ScopedTempDir temp_dir_;
@@ -109,7 +109,7 @@ TEST_F(FuchsiaCdmManagerTest, NoKeySystems) {
   base::RunLoop run_loop;
   drm::ContentDecryptionModulePtr cdm_ptr;
   cdm_ptr.set_error_handler([&](zx_status_t status) {
-    EXPECT_EQ(status, ZX_ERR_PEER_CLOSED);
+    EXPECT_EQ(status, ZX_ERR_NOT_FOUND);
     run_loop.Quit();
   });