rate limit onNewPicture to 2 per second max

This stops rapid content changes from stealing UI thread time away from
screen updates

NOTRY=true
BUG=275045

Review URL: https://chromiumcodereview.appspot.com/22884012

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@218195 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 16 insertions, 1 deletions

diff --git a/android_webview/java/src/org/chromium/android_webview/AwContentsClientCallbackHelper.java b/android_webview/java/src/org/chromium/android_webview/AwContentsClientCallbackHelper.java
index 14962ec..c792a18 100644
--- a/android_webview/java/src/org/chromium/android_webview/AwContentsClientCallbackHelper.java
+++ b/android_webview/java/src/org/chromium/android_webview/AwContentsClientCallbackHelper.java
@@ -8,6 +8,7 @@ import android.graphics.Picture;
 import android.os.Handler;
 import android.os.Looper;
 import android.os.Message;
+import android.os.SystemClock;
 
 import org.chromium.content.browser.ContentViewCore;
 
@@ -75,6 +76,13 @@ class AwContentsClientCallbackHelper {
     private final static int MSG_ON_RECEIVED_ERROR = 5;
     private final static int MSG_ON_NEW_PICTURE = 6;
 
+    // Minimum period allowed between consecutive onNewPicture calls, to rate-limit the callbacks.
+    private static final long ON_NEW_PICTURE_MIN_PERIOD_MILLIS = 500;
+    // Timestamp of the most recent onNewPicture callback.
+    private long mLastPictureTime = 0;
+    // True when a onNewPicture callback is currenly in flight.
+    private boolean mHasPendingOnNewPicture = false;
+
     private final AwContentsClient mContentsClient;
 
     private final Handler mHandler = new Handler(Looper.getMainLooper()) {
@@ -116,6 +124,8 @@ class AwContentsClientCallbackHelper {
                         throw new RuntimeException("Error getting picture", e);
                     }
                     mContentsClient.onNewPicture(picture);
+                    mLastPictureTime = SystemClock.uptimeMillis();
+                    mHasPendingOnNewPicture = false;
                     break;
                 }
                 default:
@@ -155,6 +165,11 @@ class AwContentsClientCallbackHelper {
     }
 
     public void postOnNewPicture(Callable<Picture> pictureProvider) {
-        mHandler.sendMessage(mHandler.obtainMessage(MSG_ON_NEW_PICTURE, pictureProvider));
+        if (mHasPendingOnNewPicture) return;
+        mHasPendingOnNewPicture = true;
+        long pictureTime = java.lang.Math.max(mLastPictureTime + ON_NEW_PICTURE_MIN_PERIOD_MILLIS,
+                SystemClock.uptimeMillis());
+        mHandler.sendMessageAtTime(mHandler.obtainMessage(MSG_ON_NEW_PICTURE, pictureProvider),
+                pictureTime);
     }
 }