Clear Image Decode Cache on Navigation

cc/tiles/gpu_image_decode_cache.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/tiles/gpu_image_decode_cache.h"
 
 #include <inttypes.h>
 
 #include "base/auto_reset.h"
 #include "base/debug/alias.h"
@@ skipping 566 matching lines @@
 
     // We are holding the context lock, so finish cleaning up deleted images
     // now.
     DeletePendingImages();
   } else {
     base::AutoLock lock(lock_);
     cached_bytes_limit_ = normal_max_cache_bytes_;
   }
 }
 
+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) {
   using base::trace_event::MemoryAllocatorDump;
   using base::trace_event::MemoryAllocatorDumpGuid;
   using base::trace_event::MemoryDumpLevelOfDetail;
 
   TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("cc.debug"),
                "GpuImageDecodeCache::OnMemoryDump");
 
@@ skipping 692 matching lines @@
 
 void GpuImageDecodeCache::OnPurgeMemory() {
   base::AutoLock lock(lock_);
   // Temporary changes |memory_state_| to free up cache as much as possible.
   base::AutoReset<base::MemoryState> reset(&memory_state_,
                                            base::MemoryState::SUSPENDED);
   EnsureCapacity(0);
 }
 
 }  // namespace cc