Support memory pressure handler in ImageDecodingStore

ImageDecodingStore should be responsible for its own memory pressure
policy.

Bug: 926186
Change-Id: If89cef567afd99b4274b74c3148bd45ac2d4cc5c
Reviewed-on: https://chromium-review.googlesource.com/c/1440509Reviewed-by: François Doray <fdoray@chromium.org>
Reviewed-by: Stephen Chenney <schenney@chromium.org>
Commit-Queue: Aditya Keerthi <adityakeerthi@google.com>
Cr-Commit-Position: refs/heads/master@{#627701}

third_party/blink/renderer/platform/graphics/image_decoding_store.cc

@@ -26,6 +26,7 @@
 #include "third_party/blink/renderer/platform/graphics/image_decoding_store.h"
 
 #include <memory>
+#include "base/bind.h"
 #include "third_party/blink/renderer/platform/graphics/image_frame_generator.h"
 #include "third_party/blink/renderer/platform/instrumentation/tracing/trace_event.h"
 #include "third_party/blink/renderer/platform/wtf/threading.h"
@@ -40,7 +41,10 @@ static const size_t kDefaultMaxTotalSizeOfHeapEntries = 32 * 1024 * 1024;
 
 ImageDecodingStore::ImageDecodingStore()
     : heap_limit_in_bytes_(kDefaultMaxTotalSizeOfHeapEntries),
-      heap_memory_usage_in_bytes_(0) {}
+      heap_memory_usage_in_bytes_(0),
+      memory_pressure_listener_(
+          base::BindRepeating(&ImageDecodingStore::OnMemoryPressure,
+                              base::Unretained(this))) {}
 
 ImageDecodingStore::~ImageDecodingStore() {
 #if DCHECK_IS_ON()
@@ -220,6 +224,18 @@ void ImageDecodingStore::Prune() {
   }
 }
 
+void ImageDecodingStore::OnMemoryPressure(
+    base::MemoryPressureListener::MemoryPressureLevel level) {
+  switch (level) {
+    case base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE:
+    case base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE:
+      break;
+    case base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL:
+      Clear();
+      break;
+  }
+}
+
 template <class T, class U, class V>
 void ImageDecodingStore::InsertCacheInternal(std::unique_ptr<T> cache_entry,
                                              U* cache_map,

third_party/blink/renderer/platform/graphics/image_decoding_store.h

@@ -32,6 +32,7 @@
 #include "SkSize.h"
 #include "SkTypes.h"
 #include "base/macros.h"
+#include "base/memory/memory_pressure_listener.h"
 #include "base/memory/ptr_util.h"
 #include "cc/paint/paint_image_generator.h"
 #include "third_party/blink/renderer/platform/graphics/image_frame_generator.h"
@@ -290,6 +291,10 @@ class PLATFORM_EXPORT ImageDecodingStore final {
 
   void Prune();
 
+  // Called by the memory pressure listener when the memory pressure rises.
+  void OnMemoryPressure(
+      base::MemoryPressureListener::MemoryPressureLevel level);
+
   // These helper methods are called while m_mutex is locked.
   template <class T, class U, class V>
   void InsertCacheInternal(std::unique_ptr<T> cache_entry,
@@ -347,6 +352,9 @@ class PLATFORM_EXPORT ImageDecodingStore final {
   size_t heap_limit_in_bytes_;
   size_t heap_memory_usage_in_bytes_;
 
+  // A listener to global memory pressure events.
+  base::MemoryPressureListener memory_pressure_listener_;
+
   // Protect concurrent access to these members:
   //   m_orderedCacheList
   //   m_decoderCacheMap and all CacheEntrys stored in it

third_party/blink/renderer/platform/graphics/image_decoding_store_test.cc

@@ -26,6 +26,7 @@
 #include "third_party/blink/renderer/platform/graphics/image_decoding_store.h"
 
 #include <memory>
+#include "base/memory/memory_pressure_listener.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "third_party/blink/renderer/platform/graphics/image_frame_generator.h"
 #include "third_party/blink/renderer/platform/graphics/test/mock_image_decoder.h"
@@ -233,4 +234,28 @@ TEST_F(ImageDecodingStoreTest, MultipleClientsForSameGenerator) {
   EXPECT_EQ(ImageDecodingStore::Instance().CacheEntries(), 0);
 }
 
+TEST_F(ImageDecodingStoreTest, OnMemoryPressure) {
+  std::unique_ptr<ImageDecoder> decoder = MockImageDecoder::Create(this);
+  decoder->SetSize(1, 1);
+  ImageDecodingStore::Instance().InsertDecoder(
+      generator_.get(), cc::PaintImage::kDefaultGeneratorClientId,
+      std::move(decoder));
+  EXPECT_EQ(1, ImageDecodingStore::Instance().CacheEntries());
+  EXPECT_EQ(4u, ImageDecodingStore::Instance().MemoryUsageInBytes());
+
+  base::MemoryPressureListener::SimulatePressureNotification(
+      base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE);
+  base::RunLoop().RunUntilIdle();
+
+  EXPECT_EQ(1, ImageDecodingStore::Instance().CacheEntries());
+  EXPECT_EQ(4u, ImageDecodingStore::Instance().MemoryUsageInBytes());
+
+  base::MemoryPressureListener::SimulatePressureNotification(
+      base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL);
+  base::RunLoop().RunUntilIdle();
+
+  EXPECT_EQ(0, ImageDecodingStore::Instance().CacheEntries());
+  EXPECT_EQ(0u, ImageDecodingStore::Instance().MemoryUsageInBytes());
+}
+
 }  // namespace blink

third_party/blink/renderer/platform/memory_coordinator.cc

@@ -124,10 +124,8 @@ void MemoryCoordinator::OnPurgeMemory() {
 }
 
 void MemoryCoordinator::ClearMemory() {
-  // Clear the image cache.
-  // TODO(tasak|bashi): Make ImageDecodingStore and FontCache be
-  // MemoryCoordinatorClients rather than clearing caches here.
-  ImageDecodingStore::Instance().Clear();
+  // TODO(tasak|bashi): Make FontCache a MemoryCoordinatorClient rather than
+  // clearing caches here.
   FontGlobalContext::ClearMemory();
 }