Allow task pools to reason about transparency.

cc/raster/gpu_tile_task_worker_pool.cc

Index: cc/raster/gpu_tile_task_worker_pool.cc
diff --git a/cc/raster/gpu_tile_task_worker_pool.cc b/cc/raster/gpu_tile_task_worker_pool.cc
index 0f3d6077813207b1eaed9d80dcc52e1e3268ba50..e8dc102752f01629ed6ca357042a0b492da12cb7 100644
--- a/cc/raster/gpu_tile_task_worker_pool.cc
+++ b/cc/raster/gpu_tile_task_worker_pool.cc
@@ -201,11 +201,13 @@ void GpuTileTaskWorkerPool::CheckForCompletedTasks() {
   completed_tasks_.clear();
 }
 
-ResourceFormat GpuTileTaskWorkerPool::GetResourceFormat() const {
+ResourceFormat GpuTileTaskWorkerPool::GetResourceFormat(
+    bool must_support_alpha) const {
   return rasterizer_->resource_provider()->best_render_buffer_format();
 }
 
-bool GpuTileTaskWorkerPool::GetResourceRequiresSwizzle() const {
+bool GpuTileTaskWorkerPool::GetResourceRequiresSwizzle(
+    bool must_support_alpha) const {
   // This doesn't require a swizzle because we rasterize to the correct format.
   return false;
 }