Clear Image Decode Cache on Navigation

cc/tiles/gpu_image_decode_cache.cc

Index: cc/tiles/gpu_image_decode_cache.cc
diff --git a/cc/tiles/gpu_image_decode_cache.cc b/cc/tiles/gpu_image_decode_cache.cc
index 70216a376f1a91890b4520d57f45c9cc1697d844..ce20d8af2f07b98b0b323e6637c6bf74d10342ef 100644
--- a/cc/tiles/gpu_image_decode_cache.cc
+++ b/cc/tiles/gpu_image_decode_cache.cc
@@ -584,6 +584,26 @@ void GpuImageDecodeCache::SetShouldAggressivelyFreeResources(
   }
 }
 
+void GpuImageDecodeCache::ClearCache() {
+  base::AutoLock lock(lock_);
+  for (auto it = persistent_cache_.rbegin(); it != persistent_cache_.rend();) {

[vmpstr, 2017/04/03 18:46:10]

Not that it matters, but can we make this loop forward instead of reverse, so
that it's clear that iteration order doesn't matter?

[ericrk, 2017/04/04 00:26:03]

yup - done.

+    if (it->second->decode.ref_count != 0 ||
+        it->second->upload.ref_count != 0) {
+      ++it;
+      continue;
+    }
+
+    if (it->second->upload.image()) {
+      bytes_used_ -= it->second->size;
+      images_pending_deletion_.push_back(it->second->upload.image());
+      it->second->upload.SetImage(nullptr);
+      it->second->upload.budgeted = false;
+    }
+
+    it = persistent_cache_.Erase(it);
+  }
+}
+
 bool GpuImageDecodeCache::OnMemoryDump(
     const base::trace_event::MemoryDumpArgs& args,
     base::trace_event::ProcessMemoryDump* pmd) {