media/gpu/test: Add video_encode_accelerator_perf_tests.

This CL adds a new video_encode_accelerator_perf_tests target, modeled
after the recently introduced video_decode_accelerator_perf_tests. The
new performance tests make use of the test video encoder framework, that
will greatly simplify the process of writing complex test flows.

Currently only an uncapped performance tests is added, but in the future
a capped performance tests will be introduced.

TEST=./video_encode_accelerator_perf_tests on nocturne

BUG=1045825

Change-Id: I8ff42ff54ff77d92cdf9926ec439bb8e64ee3f2a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2028873
Commit-Queue: David Staessens <dstaessens@chromium.org>
Reviewed-by: Alexandre Courbot <acourbot@chromium.org>
Reviewed-by: Hirokazu Honda <hiroh@chromium.org>
Reviewed-by: Chih-Yu Huang <akahuang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#748178}

media/gpu/BUILD.gn

@@ -557,4 +557,17 @@ if (use_v4l2_codec || use_vaapi) {
       "//testing/gtest",
     ]
   }
+
+  test("video_encode_accelerator_perf_tests") {
+    sources = [ "video_encode_accelerator_perf_tests.cc" ]
+    data = [ "//media/test/data/" ]
+    deps = [
+      ":buildflags",
+      "test:helpers",
+      "test:video_encoder",
+      "test:video_encoder_test_environment",
+      "//media:test_support",
+      "//testing/gtest",
+    ]
+  }
 }