Revert "MediaCodec: don't cache buffers until requested"

This reverts commit d59a075f79.

Reason for revert: regression (see b/235925715)
Fixes: 235925715
Bug: 189889230
Test: manual

Change-Id: I2e52c3abdd13fa0547a510b3599e082e3bff0989

media/java/android/media/MediaCodec.java

@@ -2317,6 +2317,10 @@ final public class MediaCodec {
      */
     public final void start() {
         native_start();
+        synchronized(mBufferLock) {
+            cacheBuffers(true /* input */);
+            cacheBuffers(false /* input */);
+        }
     }
     private native final void native_start();
 
@@ -3947,9 +3951,6 @@ final public class MediaCodec {
                         + "Please obtain MediaCodec.LinearBlock or HardwareBuffer "
                         + "objects and attach to QueueRequest objects.");
             }
-            if (mCachedInputBuffers == null) {
-                cacheBuffers(true /* input */);
-            }
             if (mCachedInputBuffers == null) {
                 throw new IllegalStateException();
             }
@@ -3988,9 +3989,6 @@ final public class MediaCodec {
                         + "is not compatible with CONFIGURE_FLAG_USE_BLOCK_MODEL. "
                         + "Please use getOutputFrame to get output frames.");
             }
-            if (mCachedOutputBuffers == null) {
-                cacheBuffers(false /* input */);
-            }
             if (mCachedOutputBuffers == null) {
                 throw new IllegalStateException();
             }