Raster delay UMA should exclude at-raster decodes

This CL fixes the RasterTaskSchedulingDelay UMA to not count raster
tasks that depend on at-raster image decodes. This is because measuring
the delay for them may or may not include the decode/upload time
depending on whether we do a software or a hardware decode. At-raster
image decodes should be rare enough that we don't need to consider them.

Bug: 995155
Test: this CL adds unit testing for the new behavior.
Change-Id: I040ed17f647033aeed3314c76e9ac81d5c5ed2ea
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1924613
Reviewed-by: Steven Holte <holte@chromium.org>
Reviewed-by: Khushal <khushalsagar@chromium.org>
Commit-Queue: Andres Calderon Jaramillo <andrescj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#718826}

diff --git a/cc/raster/zero_copy_raster_buffer_provider.cc b/cc/raster/zero_copy_raster_buffer_provider.cc
index ef6c2c7..4bb80dd 100644
--- a/cc/raster/zero_copy_raster_buffer_provider.cc
+++ b/cc/raster/zero_copy_raster_buffer_provider.cc

@@ -174,7 +174,8 @@
 ZeroCopyRasterBufferProvider::AcquireBufferForRaster(
     const ResourcePool::InUsePoolResource& resource,
     uint64_t resource_content_id,
-    uint64_t previous_content_id) {
+    uint64_t previous_content_id,
+    bool depends_on_at_raster_decodes) {
   if (!resource.gpu_backing()) {
     auto backing = std::make_unique<ZeroCopyGpuBacking>();
     const gpu::Capabilities& caps =