Refactor RenderView creation to use ViewMsg_New_Params.

Using a RenderViewImplParams struct to create RenderViewImpl objects was introduced in crrev.com/167341. It doesn't look necessary anymore, so I'm removing it as it adds an unnecessary step of converting one struct to another identicial one.

BUG=357747
TEST=Layout tests and content_browsertests should still work.

TBR=jochen@chromium.org

Review URL: https://codereview.chromium.org/751043002

Cr-Commit-Position: refs/heads/master@{#305545}
8 files changed