[Android, UMA, MediaFling] Add UMA for how much time users spend casting media without the media el…

chrome/android/java/src/org/chromium/chrome/browser/media/remote/AbstractMediaRouteController.java

Index: chrome/android/java/src/org/chromium/chrome/browser/media/remote/AbstractMediaRouteController.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/media/remote/AbstractMediaRouteController.java b/chrome/android/java/src/org/chromium/chrome/browser/media/remote/AbstractMediaRouteController.java
index eddf53906936b49f3d72276c9073ee662a86d691..cfa1c5bc895cb7e6beb8e7851aa1aa6f87c48b9f 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/media/remote/AbstractMediaRouteController.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/media/remote/AbstractMediaRouteController.java
@@ -8,6 +8,7 @@ import android.content.Context;
 import android.graphics.Bitmap;
 import android.net.Uri;
 import android.os.Handler;
+import android.os.SystemClock;
 import android.support.v7.media.MediaControlIntent;
 import android.support.v7.media.MediaItemStatus;
 import android.support.v7.media.MediaRouteSelector;
@@ -178,6 +179,9 @@ public abstract class AbstractMediaRouteController implements MediaRouteControll
     private final Set<UiListener> mUiListeners;
     private boolean mWatchingRouteSelection = false;
 
+    private long mMediaElementAttachedTimestampMs = 0;
+    private long mMediaElementDetachedTimestampMs = 0;
+
     protected AbstractMediaRouteController() {
 
         mDebug = CommandLine.getInstance().hasSwitch(ChromeSwitches.ENABLE_CAST_DEBUG_LOGS);
@@ -394,6 +398,29 @@ public abstract class AbstractMediaRouteController implements MediaRouteControll
         startWatchingRouteSelection();
     }
 
+    @Override
+    public void release() {
+        long remotePlaybackStoppedTimestampMs = SystemClock.uptimeMillis();
+
+        // There was no media element ever...
+        if (mMediaElementAttachedTimestampMs == 0) return;
+
+        long remotePlaybackIntervalMs =
+                remotePlaybackStoppedTimestampMs - mMediaElementAttachedTimestampMs;
+
+        if (mMediaElementDetachedTimestampMs == 0) {
+            mMediaElementDetachedTimestampMs = remotePlaybackStoppedTimestampMs;
+        }
+
+        int noElementRemotePlaybackTimePercentage =
+                (int) ((remotePlaybackStoppedTimestampMs - mMediaElementDetachedTimestampMs) * 100
+                        / remotePlaybackIntervalMs);
+        RecordCastAction.recordRemotePlaybackTimeWithoutMediaElementPercentage(
+                noElementRemotePlaybackTimePercentage);
+        mMediaElementAttachedTimestampMs = 0;
+        mMediaElementDetachedTimestampMs = 0;
+    }
+
     protected final void registerRoute(RouteInfo route) {
         mCurrentRoute = route;
 
@@ -440,6 +467,12 @@ public abstract class AbstractMediaRouteController implements MediaRouteControll
 
     @Override
     public void setMediaStateListener(MediaStateListener mediaStateListener) {

[aberent, 2016/02/04 16:44:25]

I am not sure about the sequencing of setMediaStateListener() for the new video,
and release() for the old video when switching videos. TEST that case! You might
find that the timestamps are cleared before you record them (I am almost sure
that we have other bugs in that area).
 

+        if (mMediaStateListener != null && mediaStateListener == null) {
+            mMediaElementDetachedTimestampMs = SystemClock.uptimeMillis();
+        } else if (mMediaStateListener == null && mediaStateListener != null) {
+            mMediaElementAttachedTimestampMs = SystemClock.uptimeMillis();
+        }
+
         mMediaStateListener = mediaStateListener;
     }