Add MediaServiceThrottler

media/base/android/java/src/org/chromium/media/MediaServerCrashListener.java

Index: media/base/android/java/src/org/chromium/media/MediaServerCrashListener.java
diff --git a/media/base/android/java/src/org/chromium/media/MediaServerCrashListener.java b/media/base/android/java/src/org/chromium/media/MediaServerCrashListener.java
new file mode 100644
index 0000000000000000000000000000000000000000..6db33392e99b90f6ca59da6b001efbf9562faec3
--- /dev/null
+++ b/media/base/android/java/src/org/chromium/media/MediaServerCrashListener.java
@@ -0,0 +1,111 @@
+// 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.
+
+package org.chromium.media;
+
+import android.content.Context;
+import android.media.MediaPlayer;
+
+import org.chromium.base.Log;
+import org.chromium.base.annotations.CalledByNative;
+import org.chromium.base.annotations.JNINamespace;
+import org.chromium.base.annotations.MainDex;
+import org.chromium.content.R;
+
+/**
+ * Class for listening to Android MediaServer crashes to throttle media decoding
+ * when needed.
+ */
+@MainDex
+@JNINamespace("media")
+public class MediaServerCrashListener implements MediaPlayer.OnErrorListener {
+    private static final String TAG = "crMediaCrashListener";

[DaleCurtis, 2016/11/15 00:49:32]

Don't know about the prefix, might be special in regards to some logging tools.

[tguilbert, 2016/11/15 19:29:07]

Acknowledged.

+    private static final long UNKNOWN_TIME = -1;
+
+    // Watchdog player. Used to listen to all media server crashes.
+    private MediaPlayer mPlayer;
+    private final Context mContext;
+
+    // Protecting the creation/release of the watchdog player.

[DaleCurtis, 2016/11/15 00:49:32]

As discussed offline, lets not call releaseWatchdog() from JNI, do it instead
from C++ to avoid all this locking.

[tguilbert, 2016/11/15 19:29:07]

Done.

+    private final Object mLock = new Object();
+
+    // Approximate time necessary for the MediaServer to restart after a crash.
+    private static final int APPROX_MEDIA_SERVER_RESTART_TIME_IN_MS = 5000;
+
+    // The last time we reported a failure to create the watchdog as a server crash.
+    private long mLastReportedWatchdogCreationFailure = UNKNOWN_TIME;
+
+    private long mNativeMediaServerCrashListener;
+
+    @CalledByNative
+    private static MediaServerCrashListener create(
+            Context context, long nativeMediaServerCrashListener) {
+        return new MediaServerCrashListener(context, nativeMediaServerCrashListener);
+    }
+
+    private MediaServerCrashListener(Context context, long nativeMediaServerCrashListener) {
+        mContext = context;
+        mNativeMediaServerCrashListener = nativeMediaServerCrashListener;
+    }
+
+    @CalledByNative
+    public void releaseWatchdog() {
+        synchronized (mLock) {
+            if (mPlayer != null) {
+                mPlayer.release();
+                mPlayer = null;
+            }
+        }
+    }
+
+    @CalledByNative
+    public boolean startListening() {
+        synchronized (mLock) {
+            if (mPlayer != null) return true;
+
+            try {
+                mPlayer = MediaPlayer.create(mContext, R.raw.empty);
+            } catch (IllegalStateException e) {
+                Log.e(TAG, "Exception while creating the watchdog player.", e);
+            } catch (RuntimeException e) {
+                Log.e(TAG, "Exception while creating the watchdog player.", e);
+            }
+
+            if (mPlayer != null) {
+                mPlayer.setOnErrorListener(MediaServerCrashListener.this);
+
+                // Reset the reported creation failure time on successful
+                // watchdog creation.
+                mLastReportedWatchdogCreationFailure = UNKNOWN_TIME;
+                return true;
+            }
+
+            long currentTime = SystemClock.elapsedRealtime();
+
+            // It takes ~5s for the MediaServer to restart. Do not report a
+            // failure to create a watchdog MediaPlayer as a crash more than
+            // once per 5s, to prevent a burst of calls to startListening() from
+            // artificially inflating the number of crashes.
+            if (mLastReportedWatchdogCreationFailure == UNKNOWN_TIME
+                    || (currentTime - mLastReportedWatchdogCreationFailure)
+                            > APPROX_MEDIA_SERVER_RESTART_TIME_IN_MS) {
+                Log.e(TAG, "Unable to create watchdog player, treating it as server crash.");
+                nativeOnMediaServerCrashDetected(mNativeMediaServerCrashListener);
+                mLastReportedWatchdogCreationFailure = currentTime;
+            }
+            return false;
+        }
+    }
+
+    @Override
+    public boolean onError(MediaPlayer mp, int what, int extra) {
+        if (what == MediaPlayer.MEDIA_ERROR_SERVER_DIED) {
+            nativeOnMediaServerCrashDetected(mNativeMediaServerCrashListener);
+            releaseWatchdog();
+        }
+        return true;
+    }
+
+    private native void nativeOnMediaServerCrashDetected(long nativeMediaServerCrashListener);
+}