cc: Remove render_pass_test_common, move to render_pass_test_utils.

The common file had a single method, while the utils has 6. Move that
one method over to the utils file, and drop the TestRenderPass type.

R=enne, vmpstr, weiliangc
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/1291363003

Cr-Commit-Position: refs/heads/master@{#344014}

• cc/BUILD.gn[diff]
• cc/cc_tests.gyp[diff]
• cc/layers/delegated_renderer_layer_impl_unittest.cc[diff]
• cc/output/delegating_renderer_unittest.cc[diff]
• cc/output/gl_renderer_unittest.cc[diff]
• cc/output/software_renderer_unittest.cc[diff]
• cc/quads/render_pass_unittest.cc[diff]
• cc/surfaces/surface_aggregator_test_helpers.cc[diff]
• cc/surfaces/surface_aggregator_unittest.cc[diff]
• cc/test/render_pass_test_common.cc[Deleted - diff]
• cc/test/render_pass_test_common.h[Deleted - diff]
• cc/test/render_pass_test_utils.cc[diff]
• cc/test/render_pass_test_utils.h[diff]
• cc/trees/layer_tree_host_impl_unittest.cc[diff]
• cc/trees/layer_tree_host_unittest_context.cc[diff]