Improve linearized pdf load/show time.

pdf/timer.h

Index: pdf/timer.h
diff --git a/pdf/timer.h b/pdf/timer.h
new file mode 100644
index 0000000000000000000000000000000000000000..525f069c2a1253b4b1eda22d48aa9a70bc0fa6ed
--- /dev/null
+++ b/pdf/timer.h
@@ -0,0 +1,35 @@
+// Copyright 2016 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.
+
+#ifndef PDF_TIMER_H_
+#define PDF_TIMER_H_
+
+#include <set>

[Lei Zhang, 2016/10/25 18:24:52]

Not used.

[snake, 2016/10/25 19:16:27]

Done.

+
+#include "base/macros.h"
+#include "ppapi/utility/completion_callback_factory.h"
+
+namespace chrome_pdf {
+
+class Timer {

[Lei Zhang, 2016/10/25 18:24:52]

Please add a description for this class. Looks like this is a repeating timer?
It will be helpful to mention why we can't use base::Timer.

[snake, 2016/10/25 19:16:27]

Done.

+ public:
+  explicit Timer(int delay);

[Lei Zhang, 2016/10/25 18:24:52]

What unit is |delay| in? Rename to "delay_in_milliseconds" to match the
CallOnMainThread() parameter?

[snake, 2016/10/25 19:16:27]

Done.

+  virtual ~Timer();
+
+  virtual void OnTimer() = 0;
+
+ private:
+  friend class TestTimerRunner;

[Lei Zhang, 2016/10/25 18:24:52]

Add this in the next CL.

[snake, 2016/10/25 19:16:27]

Done.

+  void PostCallback();
+  void TimerProc(int32_t result);
+
+  int delay_;
+  pp::CompletionCallbackFactory<Timer> callback_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(Timer);
+};
+
+}  // namespace chrome_pdf
+
+#endif  // PDF_TIMER_H_