Avoid OOPR for the WebP YUV path until that part is completed.

Out-of-process rasterization is enabled by default on perf bots,
but means the YUV decoding path will be avoided until that branch
is implemented.

Bug: 900264
Change-Id: Ideaa78856fc754be3436d8fecd3589b127016d2f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1626504Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Reviewed-by: Khushal <khushalsagar@chromium.org>
Commit-Queue: Madeleine Barowsky <mbarowsky@chromium.org>
Auto-Submit: Madeleine Barowsky <mbarowsky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#664434}

tools/perf/page_sets/rendering/rendering_stories.py

@@ -57,10 +57,13 @@ class RenderingStorySet(story.StorySet):
         # 'backdrop-filter' CSS property to work.
         required_args.append('--enable-experimental-web-platform-features')
 
+      # TODO(crbug.com/968125): We must run without out-of-process rasterization
+      # until that branch is implemented for YUV decoding.
       if (story_class.TAGS and
           story_tags.IMAGE_DECODING in story_class.TAGS and
           story_tags.GPU_RASTERIZATION in story_class.TAGS):
-        required_args.append('--force-gpu-rasterization')
+        required_args += ['--force-gpu-rasterization',
+                          '--disable--oop-rasterization']
         # Run RGB decoding with GPU rasterization (to be most comparable to YUV)
         self.AddStory(story_class(
             page_set=self,