Set up cache in vulkan to reuse GrVkPrograms (aka VkPipelines)

src/gpu/vk/GrVkRenderPass.cpp

Index: src/gpu/vk/GrVkRenderPass.cpp
diff --git a/src/gpu/vk/GrVkRenderPass.cpp b/src/gpu/vk/GrVkRenderPass.cpp
index 958d604f546c658a502ee4670a2a4f22f8d37512..c435599676eacdf21d4a48fcd33a3b8a0d80f9f0 100644
--- a/src/gpu/vk/GrVkRenderPass.cpp
+++ b/src/gpu/vk/GrVkRenderPass.cpp
@@ -7,6 +7,7 @@
 
 #include "GrVkRenderPass.h"
 
+#include "GrProcessor.h"
 #include "GrVkFramebuffer.h"
 #include "GrVkGpu.h"
 #include "GrVkRenderTarget.h"
@@ -218,3 +219,20 @@ bool GrVkRenderPass::isCompatible(const GrVkRenderTarget& target) const {
 
     return true;
 }
+
+void GrVkRenderPass::genKey(GrProcessorKeyBuilder* b) const {
+    b->add32(fAttachmentFlags);
+    if (fAttachmentFlags & kColor_AttachmentFlag) {
+        b->add32(fAttachmentsDescriptor.fColor.fFormat);
+        b->add32(fAttachmentsDescriptor.fColor.fSamples);
+    }
+    if (fAttachmentFlags & kResolve_AttachmentFlag) {
+        b->add32(fAttachmentsDescriptor.fResolve.fFormat);
+        b->add32(fAttachmentsDescriptor.fResolve.fSamples);
+    }
+    if (fAttachmentFlags & kStencil_AttachmentFlag) {
+        b->add32(fAttachmentsDescriptor.fStencil.fFormat);
+        b->add32(fAttachmentsDescriptor.fStencil.fSamples);
+    }
+}
+