Add PluginMessageLoopProxy and use it for Host plugin UI thread.

remoting/base/plugin_message_loop_proxy.cc

Index: remoting/base/plugin_message_loop_proxy.cc
diff --git a/remoting/base/plugin_message_loop_proxy.cc b/remoting/base/plugin_message_loop_proxy.cc
new file mode 100644
index 0000000000000000000000000000000000000000..4ea94d95004253c5de767bab9733bdbf4ff294b9
--- /dev/null
+++ b/remoting/base/plugin_message_loop_proxy.cc
@@ -0,0 +1,109 @@
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "remoting/base/plugin_message_loop_proxy.h"
+
+namespace remoting {
+
+PluginMessageLoopProxy::PluginMessageLoopProxy(Delegate* delegate)
+    : delegate_(delegate) {
+}
+
+PluginMessageLoopProxy::~PluginMessageLoopProxy() {
+}
+
+void PluginMessageLoopProxy::Detach() {
+  base::AutoLock auto_lock(lock_);
+  delegate_ = NULL;
+}
+
+// MessageLoopProxy interface implementation.
+bool PluginMessageLoopProxy::PostTask(
+    const tracked_objects::Location& from_here,
+    Task* task) {
+  return PostDelayedTask(from_here, task, 0);
+}
+
+bool PluginMessageLoopProxy::PostDelayedTask(
+    const tracked_objects::Location& from_here,
+    Task* task,
+    int64 delay_ms) {
+  base::AutoLock auto_lock(lock_);
+  if (!delegate_) {
+    return false;
+  } else {
+    return delegate_->RunOnPluginThread(
+        delay_ms, &PluginMessageLoopProxy::RunTask, task);
+  }
+}
+
+bool PluginMessageLoopProxy::PostNonNestableTask(
+    const tracked_objects::Location& from_here,
+    Task* task) {
+  // All tasks running on this message loop are non-nestable.
+  return PostTask(from_here, task);

[awong, 2011/08/12 21:15:26]

I'm not certain we should even allow this API to be called without a CHECK
failure.

Given that we're just delegating to the plugin thread, and that servicing
synchronous Javascript is one of the main reasons we use nested message loops, I
don't think we can guarantee that the task can't be nested...

[Sergey Ulanov, 2011/08/12 22:45:26]

That is right, but tasks scheduled with this proxy will never call
MessageLoop::Run(), so for whoever uses this object nested and non-nested tasks
will look the same, i.e. one task posted with this proxy will never be nested in
another tasks posted using this proxy. Or am I missing some other subtle
differences between nested and non-nested tasks?

+}
+
+bool PluginMessageLoopProxy::PostNonNestableDelayedTask(
+      const tracked_objects::Location& from_here,
+      Task* task,
+      int64 delay_ms) {
+  // All tasks running on this message loop are non-nestable.
+  return PostDelayedTask(from_here, task, delay_ms);
+}
+
+bool PluginMessageLoopProxy::PostTask(
+    const tracked_objects::Location& from_here,
+    const base::Closure& task) {
+  return PostDelayedTask(from_here, task, 0);
+}
+
+bool PluginMessageLoopProxy::PostDelayedTask(
+    const tracked_objects::Location& from_here,
+    const base::Closure& task,
+    int64 delay_ms) {
+  base::AutoLock auto_lock(lock_);
+  if (!delegate_) {
+    return false;
+  } else {
+    base::Closure* task_in_heap = new base::Closure(task);

[awong, 2011/08/12 21:15:26]

task_in_heap -> task_on_heap

[Sergey Ulanov, 2011/08/12 22:45:26]

Done.

+    return delegate_->RunOnPluginThread(
+        delay_ms, &PluginMessageLoopProxy::RunClosure, task_in_heap);
+  }
+}
+
+bool PluginMessageLoopProxy::PostNonNestableTask(
+    const tracked_objects::Location& from_here,
+    const base::Closure& task) {
+  // All tasks running on this message loop are non-nestable.
+  return PostTask(from_here, task);
+}
+
+bool PluginMessageLoopProxy::PostNonNestableDelayedTask(
+    const tracked_objects::Location& from_here,
+    const base::Closure& task,
+    int64 delay_ms) {
+  // All tasks running on this message loop are non-nestable.
+  return PostDelayedTask(from_here, task, delay_ms);
+}
+
+bool PluginMessageLoopProxy::BelongsToCurrentThread() {
+  return delegate_->IsPluginThread();
+}
+
+// static
+void PluginMessageLoopProxy::RunTask(void* data) {
+  Task* task = reinterpret_cast<Task*>(data);
+  task->Run();
+  delete task;
+}
+
+// static
+void PluginMessageLoopProxy::RunClosure(void* data) {
+  base::Closure* task = reinterpret_cast<base::Closure*>(data);
+  task->Run();
+  delete task;
+}
+
+}  // namespace remoting