[core] Display modify, expires debug information

src/mbgl/renderer/debug_bucket.cpp

@@ -1,6 +1,7 @@
 #include <mbgl/renderer/debug_bucket.hpp>
 #include <mbgl/renderer/painter.hpp>
 #include <mbgl/shader/plain_shader.hpp>
+#include <mbgl/util/time.hpp>
 
 #include <mbgl/platform/gl.hpp>
 
@@ -9,9 +10,20 @@
 
 using namespace mbgl;
 
-DebugBucket::DebugBucket(const TileID id, const TileData::State state_) : state(state_) {
+DebugBucket::DebugBucket(const TileID id, const TileData::State state_, Seconds modified_, Seconds expires_)
+    : state(state_),
+      modified(modified_),
+      expires(expires_) {
     const std::string text = std::string(id) + " - " + TileData::StateToString(state);
     fontBuffer.addText(text.c_str(), 50, 200, 5);
+
+    if (modified > Seconds::zero() && expires > Seconds::zero()) {
+        const std::string modifiedText = "modified: " + util::iso8601(modified.count());
+        fontBuffer.addText(modifiedText.c_str(), 50, 400, 5);
+
+        const std::string expiresText = "expires: " + util::iso8601(expires.count());
+        fontBuffer.addText(expiresText.c_str(), 50, 600, 5);
+    }
 }
 
 void DebugBucket::drawLines(PlainShader& shader) {