oop: Create a RasterInterface, and use it for Compositor Worker contexts.

This CL enables RasterInterface for Compositor Worker contexts in
content/renderer and content/browser.

RasterInterface provides a subset of GLES2Interface APIs required for
OOP Rasterization.  This will gradually diverge away from GLES2.

The initial change adds a client-side implementation of
RasterInterface on top of GLES2Interface.

Design Doc: https://goo.gl/Q6E1ZC
BUG=757607

Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.android:android_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel
Change-Id: Iaefd861f0c51b9995ad27eb94de2068d0f9dab22
Reviewed-on: https://chromium-review.googlesource.com/778242
Commit-Queue: Victor Miura <vmiura@chromium.org>
Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Reviewed-by: danakj <danakj@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: vmpstr <vmpstr@chromium.org>
Reviewed-by: Bo <boliu@chromium.org>
Reviewed-by: Eric Karl <ericrk@chromium.org>
Reviewed-by: Antoine Labour <piman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#523700}

diff --git a/cc/BUILD.gn b/cc/BUILD.gn
index 168a79e..40a6486 100644
--- a/cc/BUILD.gn
+++ b/cc/BUILD.gn

@@ -363,6 +363,7 @@
     "//gpu",
     "//gpu/command_buffer/client:gles2_implementation",
     "//gpu/command_buffer/client:gles2_interface",
+    "//gpu/command_buffer/client:raster_interface",
     "//gpu/ipc:gl_in_process_context",
     "//gpu/skia_bindings:skia_bindings",
     "//gpu/vulkan:features",
@@ -728,6 +729,7 @@
     "//gpu:test_support",
     "//gpu/command_buffer/client:gles2_implementation",
     "//gpu/command_buffer/client:gles2_interface",
+    "//gpu/command_buffer/client:raster_interface",
     "//gpu/command_buffer/common:gles2_utils",
     "//gpu/ipc:gl_in_process_context",
     "//gpu/skia_bindings",
@@ -780,6 +782,7 @@
     "//components/viz/test:test_support",
     "//gpu",
     "//gpu:test_support",
+    "//gpu/command_buffer/client:gles2_implementation",
     "//gpu/command_buffer/common:gles2_utils",
     "//media",
     "//mojo/edk/system",