Fix small issues that stops the Chromium DEPS roll.

Some imports of classes in the same package are a bit silly.

Removing = false for booleans is safe because Java guarantees that
an uninitialized bool will always be false.

Tbr: sakal@chromium.org
Bug: None
Change-Id: I04baa78a6e21b1c4fc74c5e46665e66481da2495
Reviewed-on: https://webrtc-review.googlesource.com/c/111243
Reviewed-by: Patrik Höglund <phoglund@webrtc.org>
Commit-Queue: Patrik Höglund <phoglund@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25678}

sdk/android/src/java/org/webrtc/NativeCapturerObserver.java

@@ -11,6 +11,7 @@
 package org.webrtc;
 
 import javax.annotation.Nullable;
+import org.webrtc.VideoFrame;
 
 /**
  * Implements VideoCapturer.CapturerObserver and feeds frames to