Use git hash as fingerprint for getting caching interfaces.

- Also changes to use string_view for the constexpr hash.

Bug: dawn:549
Change-Id: I1ded4994d501f0378d3fa8f5c16d07e3c566270f
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/92962
Reviewed-by: Austin Eng <enga@chromium.org>
Commit-Queue: Loko Kung <lokokung@google.com>

generator/templates/dawn/common/Version.h

@@ -15,9 +15,11 @@
 #ifndef COMMON_VERISON_AUTOGEN_H_
 #define COMMON_VERISON_AUTOGEN_H_
 
+#include <string_view>
+
 namespace dawn {
 
-static constexpr char kGitHash[] = "{{get_gitHash()}}";
+static constexpr std::string_view kGitHash("{{get_gitHash()}}");
 
 } // namespace dawn
 

src/dawn/native/Instance.cpp

@@ -20,6 +20,7 @@
 #include "dawn/common/GPUInfo.h"
 #include "dawn/common/Log.h"
 #include "dawn/common/SystemUtils.h"
+#include "dawn/common/Version_autogen.h"
 #include "dawn/native/ChainUtils_autogen.h"
 #include "dawn/native/ErrorData.h"
 #include "dawn/native/Surface.h"
@@ -94,9 +95,8 @@ BackendsBitset GetEnabledBackends() {
 }
 
 dawn::platform::CachingInterface* GetCachingInterface(dawn::platform::Platform* platform) {
-    if (platform != nullptr) {
-        return platform->GetCachingInterface(/*fingerprint*/ nullptr,
-                                             /*fingerprintSize*/ 0);
+    if (platform != nullptr && dawn::kGitHash.size() > 0) {
+        return platform->GetCachingInterface(dawn::kGitHash.data(), dawn::kGitHash.size());
     }
     return nullptr;
 }