Reset isFirstFrameRendered on init of SurfaceViewRenderer

If a SurfaceViewRenderer is reinitialized, the onFirstFrameRendered
callback is not fired.

Ensure that we reset the flag when the SurfaceViewRenderer is
initialized.

BUG=webrtc:7985

Review-Url: https://codereview.webrtc.org/2981793002
Cr-Commit-Position: refs/heads/master@{#19016}

AUTHORS

@@ -10,6 +10,7 @@ Anil Kumar <an1kumar@gmail.com>
 Ben Strong <bstrong@gmail.com>
 Bob Withers <bwit@pobox.com>
 Bridger Maxwell <bridgeyman@gmail.com>
+Chris Tserng <tserng@amazon.com>
 Christophe Dumez <ch.dumez@samsung.com>
 Cody Barnes <conceptgenesis@gmail.com>
 Colin Plumb

webrtc/sdk/android/api/org/webrtc/SurfaceViewRenderer.java

@@ -92,6 +92,7 @@ public class SurfaceViewRenderer
     ThreadUtils.checkIsOnMainThread();
     this.rendererEvents = rendererEvents;
     synchronized (layoutLock) {
+      isFirstFrameRendered = false;
       rotatedFrameWidth = 0;
       rotatedFrameHeight = 0;
       frameRotation = 0;