Add support for creating HW codecs in the VideoProcessor tests.

This CL adds the ability to _create_ HW codecs (Android and iOS) in the
VideoProcessor integration tests. Since the VideoProcessor class is not thread
safe yet, this CL does not add the ability to _use_ HW codecs in the tests. A
follow-up CL is planned that will add this ability.

This CL further adds a separate build target which is used to separate the
"plot" versions of the integration tests from the "correctness" versions. The
former will be run manually on devices, whereas the latter are used on the
trybots/buildbots to find regressions in the SW codecs. The underlying test
is the same, however.

BUG=webrtc:6634

Review-Url: https://codereview.webrtc.org/2695653002
Cr-Commit-Position: refs/heads/master@{#16716}

webrtc/modules/video_coding/DEPS

@@ -8,3 +8,14 @@ include_rules = [
   "+webrtc/system_wrappers",
   "+webrtc/tools",
 ]
+
+specific_include_rules = {
+  "android_test_initializer\.cc": [
+    "+base/android",
+    "+webrtc/sdk",
+  ],
+  "(.*test\.cc|.*test\.h)": [
+     "+webrtc/media/engine",
+     "+webrtc/sdk",
+  ],
+}