Allow creation of TextureMailboxDeleter without a task runner.

In this case, the deletion will happen on the current thread. This is necessary for android webview, because the Display lives on a thread without a task runner.
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/1158563005

Cr-Commit-Position: refs/heads/master@{#331870}

4 files changed, 36 insertions, 5 deletions

diff --git a/cc/output/texture_mailbox_deleter.cc b/cc/output/texture_mailbox_deleter.cc
index aaf2a0e..7729c4e 100644
--- a/cc/output/texture_mailbox_deleter.cc
+++ b/cc/output/texture_mailbox_deleter.cc
@@ -65,9 +65,13 @@ scoped_ptr<SingleReleaseCallback> TextureMailboxDeleter::GetReleaseCallback(
 
   // Provide a callback for the main thread that posts back to the impl
   // thread.
-  scoped_ptr<SingleReleaseCallback> main_callback =
-      SingleReleaseCallback::Create(base::Bind(
-          &PostTaskFromMainToImplThread, impl_task_runner_, run_impl_callback));
+  scoped_ptr<SingleReleaseCallback> main_callback;
+  if (impl_task_runner_) {
+    main_callback = SingleReleaseCallback::Create(base::Bind(
+        &PostTaskFromMainToImplThread, impl_task_runner_, run_impl_callback));
+  } else {
+    main_callback = SingleReleaseCallback::Create(run_impl_callback);
+  }
 
   return main_callback.Pass();
 }
diff --git a/cc/output/texture_mailbox_deleter.h b/cc/output/texture_mailbox_deleter.h
index 2865126..19760ea 100644
--- a/cc/output/texture_mailbox_deleter.h
+++ b/cc/output/texture_mailbox_deleter.h
@@ -19,6 +19,8 @@ class SingleReleaseCallback;
 
 class CC_EXPORT TextureMailboxDeleter {
  public:
+  // task_runner corresponds with the thread the delete task should be posted
+  // to. If null, the delete will happen on the calling thread.
   explicit TextureMailboxDeleter(
       const scoped_refptr<base::SingleThreadTaskRunner>& task_runner);
   ~TextureMailboxDeleter();
diff --git a/cc/output/texture_mailbox_deleter_unittest.cc b/cc/output/texture_mailbox_deleter_unittest.cc
index 34d8595..37b9712 100644
--- a/cc/output/texture_mailbox_deleter_unittest.cc
+++ b/cc/output/texture_mailbox_deleter_unittest.cc
@@ -44,5 +44,31 @@ TEST(TextureMailboxDeleterTest, Destroy) {
   cb->Run(0, false);
 }
 
+TEST(TextureMailboxDeleterTest, NullTaskRunner) {
+  scoped_ptr<TextureMailboxDeleter> deleter(new TextureMailboxDeleter(nullptr));
+
+  scoped_refptr<TestContextProvider> context_provider =
+      TestContextProvider::Create();
+  context_provider->BindToCurrentThread();
+
+  GLuint texture_id = 0u;
+  context_provider->ContextGL()->GenTextures(1, &texture_id);
+
+  EXPECT_TRUE(context_provider->HasOneRef());
+  EXPECT_EQ(1u, context_provider->TestContext3d()->NumTextures());
+
+  scoped_ptr<SingleReleaseCallback> cb =
+      deleter->GetReleaseCallback(context_provider, texture_id);
+  EXPECT_FALSE(context_provider->HasOneRef());
+  EXPECT_EQ(1u, context_provider->TestContext3d()->NumTextures());
+
+  cb->Run(0, false);
+
+  // With no task runner the callback will immediately drops its ref on the
+  // ContextProvider and delete the texture.
+  EXPECT_TRUE(context_provider->HasOneRef());
+  EXPECT_EQ(0u, context_provider->TestContext3d()->NumTextures());
+}
+
 }  // namespace
 }  // namespace cc
diff --git a/cc/surfaces/display.cc b/cc/surfaces/display.cc
index ca35b67..fadb165 100644
--- a/cc/surfaces/display.cc
+++ b/cc/surfaces/display.cc
@@ -35,8 +35,7 @@ Display::Display(DisplayClient* client,
       device_scale_factor_(1.f),
       swapped_since_resize_(false),
       scheduler_(nullptr),
-      texture_mailbox_deleter_(
-          new TextureMailboxDeleter(base::ThreadTaskRunnerHandle::Get())) {
+      texture_mailbox_deleter_(new TextureMailboxDeleter(nullptr)) {
   manager_->AddObserver(this);
 }