modules/video_coding refactorings

The main purpose was the interface-> include rename, but other files
were also moved, eliminating the "main" dir.

To avoid breaking downstream, the "interface" directories were copied
into a new "video_coding/include" dir. The old headers got pragma
warnings added about deprecation (a very short deprecation since I plan
to remove them as soon downstream is updated).

Other files also moved:
video_coding/main/source -> video_coding
video_coding/main/test -> video_coding/test

BUG=webrtc:5095
TESTED=Passing compile-trybots with --clobber flag:
git cl try --clobber --bot=win_compile_rel --bot=linux_compile_rel --bot=android_compile_rel --bot=mac_compile_rel --bot=ios_rel --bot=linux_gn_rel --bot=win_x64_gn_rel --bot=mac_x64_gn_rel --bot=android_gn_rel -m tryserver.webrtc

R=stefan@webrtc.org, tommi@webrtc.org

Review URL: https://codereview.webrtc.org/1417283007 .

Cr-Commit-Position: refs/heads/master@{#10694}
diff --git a/webrtc/modules/video_coding/codec_timer.cc b/webrtc/modules/video_coding/codec_timer.cc
new file mode 100644
index 0000000..e987594
--- /dev/null
+++ b/webrtc/modules/video_coding/codec_timer.cc
@@ -0,0 +1,129 @@
+/*
+ *  Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "webrtc/modules/video_coding/codec_timer.h"
+
+#include <assert.h>
+
+namespace webrtc
+{
+
+// The first kIgnoredSampleCount samples will be ignored.
+static const int32_t kIgnoredSampleCount = 5;
+
+VCMCodecTimer::VCMCodecTimer()
+:
+_filteredMax(0),
+_ignoredSampleCount(0),
+_shortMax(0),
+_history()
+{
+    Reset();
+}
+
+void VCMCodecTimer::Reset()
+{
+    _filteredMax = 0;
+    _ignoredSampleCount = 0;
+    _shortMax = 0;
+    for (int i=0; i < MAX_HISTORY_SIZE; i++)
+    {
+        _history[i].shortMax = 0;
+        _history[i].timeMs = -1;
+    }
+}
+
+// Update the max-value filter
+void VCMCodecTimer::MaxFilter(int32_t decodeTime, int64_t nowMs)
+{
+    if (_ignoredSampleCount >= kIgnoredSampleCount)
+    {
+        UpdateMaxHistory(decodeTime, nowMs);
+        ProcessHistory(nowMs);
+    }
+    else
+    {
+        _ignoredSampleCount++;
+    }
+}
+
+void
+VCMCodecTimer::UpdateMaxHistory(int32_t decodeTime, int64_t now)
+{
+    if (_history[0].timeMs >= 0 &&
+        now - _history[0].timeMs < SHORT_FILTER_MS)
+    {
+        if (decodeTime > _shortMax)
+        {
+            _shortMax = decodeTime;
+        }
+    }
+    else
+    {
+        // Only add a new value to the history once a second
+        if(_history[0].timeMs == -1)
+        {
+            // First, no shift
+            _shortMax = decodeTime;
+        }
+        else
+        {
+            // Shift
+            for(int i = (MAX_HISTORY_SIZE - 2); i >= 0 ; i--)
+            {
+                _history[i+1].shortMax = _history[i].shortMax;
+                _history[i+1].timeMs = _history[i].timeMs;
+            }
+        }
+        if (_shortMax == 0)
+        {
+            _shortMax = decodeTime;
+        }
+
+        _history[0].shortMax = _shortMax;
+        _history[0].timeMs = now;
+        _shortMax = 0;
+    }
+}
+
+void
+VCMCodecTimer::ProcessHistory(int64_t nowMs)
+{
+    _filteredMax = _shortMax;
+    if (_history[0].timeMs == -1)
+    {
+        return;
+    }
+    for (int i=0; i < MAX_HISTORY_SIZE; i++)
+    {
+        if (_history[i].timeMs == -1)
+        {
+            break;
+        }
+        if (nowMs - _history[i].timeMs > MAX_HISTORY_SIZE * SHORT_FILTER_MS)
+        {
+            // This sample (and all samples after this) is too old
+            break;
+        }
+        if (_history[i].shortMax > _filteredMax)
+        {
+            // This sample is the largest one this far into the history
+            _filteredMax = _history[i].shortMax;
+        }
+    }
+}
+
+// Get the maximum observed time within a time window
+int32_t VCMCodecTimer::RequiredDecodeTimeMs(FrameType /*frameType*/) const
+{
+    return _filteredMax;
+}
+
+}