sf-latency: Write a benchmark for RenderEngine

Bug: 193240340
Test: mmma -j frameworks/native/libs/renderengine/bench/
      && adb push out/.../librenderengine_bench
                  /data/.../librenderengine_bench
      && adb shell /data/.../librenderengine_bench

Write a benchmark using Google-Benchmark to track the performance of
RenderEngine.

RenderEngineBench.cpp:
- Contains the benchmarks to run.
- Write a helper function that times calls to RenderEngine::drawLayers.
- Write a single benchmark that times drawing a mock homescreen plus a
  blur layer, using a blur radius used in practice.
  Decode the homescreen into a buffer with CPU support, and then copy it
  to one without, which better represents actual use.
- Use RenderEngineType to determine which subclass to benchmark. The
  only existing benchmark uses SKIA_GL, since we intend to time just
  drawLayers, but future benchmarks will want to time threading aspects
  with SKIA_GL_THREADED, and we may add more RenderEngineTypes in the
  future.

Codec.cpp:
- Write methods for decoding and encoding a buffer.

Flags.cpp:
- Extra flags that can be passed to the executable.
- --save allows encoding the result to a file to verify it looks as
  intended.
- parse --help to describe --save and any future flags specific to
  RenderEngineBench.

RenderEngineBench.h:
- header file for methods used across cpp files. Use a single common
  header since otherwise we would have several small headers.

homescreen.png:
- Mock homescreen to draw in drawLayers

Change-Id: I81a1a8a30a1c20985bbf066d2ba4d5f1fd1f6dc3
diff --git a/libs/renderengine/benchmark/RenderEngineBench.h b/libs/renderengine/benchmark/RenderEngineBench.h
new file mode 100644
index 0000000..1a25d77
--- /dev/null
+++ b/libs/renderengine/benchmark/RenderEngineBench.h
@@ -0,0 +1,65 @@
+/*
+ * Copyright 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <ui/GraphicBuffer.h>
+
+using namespace android;
+
+/**
+ * Utilities for running benchmarks.
+ */
+namespace renderenginebench {
+/**
+ * Parse RenderEngineBench-specific flags from the command line.
+ *
+ * --save Save the output buffer to a file to verify that it drew as
+ *  expected.
+ */
+void parseFlags(int argc, char** argv);
+
+/**
+ * Parse flags for '--help'
+ */
+void parseFlagsForHelp(int argc, char** argv);
+
+/**
+ * Whether to save the drawing result to a file.
+ *
+ * True if --save was used on the command line.
+ */
+bool save();
+
+/**
+ * Decode the image at 'path' into 'buffer'.
+ *
+ * Currently only used for debugging. The image will be scaled to fit the
+ * buffer if necessary.
+ *
+ * This assumes the buffer matches ANDROID_BITMAP_FORMAT_RGBA_8888.
+ *
+ * @param path Relative to the directory holding the executable.
+ */
+void decode(const char* path, const sp<GraphicBuffer>& buffer);
+
+/**
+ * Encode the buffer to a jpeg.
+ *
+ * This assumes the buffer matches ANDROID_BITMAP_FORMAT_RGBA_8888.
+ *
+ * @param path Relative to the directory holding the executable.
+ */
+void encodeToJpeg(const char* path, const sp<GraphicBuffer>& buffer);
+} // namespace renderenginebench