Dawn: implement Sampler cache (optimization).

Change-Id: I0b1fabadb3fddd90350eff3b13037ce92c5dbfd8
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/238178
Commit-Queue: Stephen White <senorblanco@chromium.org>
Reviewed-by: Greg Daniel <egdaniel@google.com>
diff --git a/src/gpu/dawn/GrDawnProgramDataManager.cpp b/src/gpu/dawn/GrDawnProgramDataManager.cpp
index 573cb98..db22f25 100644
--- a/src/gpu/dawn/GrDawnProgramDataManager.cpp
+++ b/src/gpu/dawn/GrDawnProgramDataManager.cpp
@@ -18,6 +18,8 @@
     , fFragmentUniformsDirty(false) {
     fGeometryUniformData.reset(geometryUniformSize);
     fFragmentUniformData.reset(fragmentUniformSize);
+    memset(fGeometryUniformData.get(), 0, fGeometryUniformSize);
+    memset(fFragmentUniformData.get(), 0, fFragmentUniformSize);
     int count = uniforms.count();
     fUniforms.push_back_n(count);
     // We must add uniforms in same order is the UniformInfoArray so that UniformHandles already