content: Add DeletedDiscardableSharedMemory IPC.

This provides a mechanism for child processes to notify the
browser process that a discardable memory segment has been
deleted. This reduces the chance of the browser unnecessarily
purging a memory segment that is still useful and it makes
total discardable memory usage stats in the browser process
better match current usage by all child processes.

BUG=
TEST=content_unittests --gtest_filter=DiscardableSharedMemoryHeapTest.DeletedCallback, content_browsertests --gtest_filter=ChildDiscardableSharedMemoryManagerBrowserTest.ReleaseFreeMemory

Review URL: https://codereview.chromium.org/1009203004

Cr-Commit-Position: refs/heads/master@{#320848}

1 files changed, 37 insertions, 8 deletions

diff --git a/content/common/discardable_shared_memory_heap_unittest.cc b/content/common/discardable_shared_memory_heap_unittest.cc
index 6a01b27..5297ded 100644
--- a/content/common/discardable_shared_memory_heap_unittest.cc
+++ b/content/common/discardable_shared_memory_heap_unittest.cc
@@ -4,6 +4,7 @@
 
 #include "content/common/discardable_shared_memory_heap.h"
 
+#include "base/bind.h"
 #include "base/memory/discardable_shared_memory.h"
 #include "base/process/process_metrics.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ -11,6 +12,9 @@
 namespace content {
 namespace {
 
+void NullTask() {
+}
+
 TEST(DiscardableSharedMemoryHeapTest, Basic) {
   size_t block_size = base::GetPageSize();
   DiscardableSharedMemoryHeap heap(block_size);
@@ -33,7 +37,7 @@ TEST(DiscardableSharedMemoryHeapTest, Basic) {
 
   // Create new span for memory.
   scoped_ptr<DiscardableSharedMemoryHeap::Span> new_span(
-      heap.Grow(memory.Pass(), memory_size));
+      heap.Grow(memory.Pass(), memory_size, base::Bind(NullTask)));
 
   // Size should match |memory_size|.
   EXPECT_EQ(memory_size, heap.GetSize());
@@ -76,7 +80,7 @@ TEST(DiscardableSharedMemoryHeapTest, SplitAndMerge) {
       new base::DiscardableSharedMemory);
   ASSERT_TRUE(memory->CreateAndMap(memory_size));
   scoped_ptr<DiscardableSharedMemoryHeap::Span> new_span(
-      heap.Grow(memory.Pass(), memory_size));
+      heap.Grow(memory.Pass(), memory_size, base::Bind(NullTask)));
 
   // Split span into two.
   scoped_ptr<DiscardableSharedMemoryHeap::Span> leftover =
@@ -131,7 +135,7 @@ TEST(DiscardableSharedMemoryHeapTest, MergeSingleBlockSpan) {
       new base::DiscardableSharedMemory);
   ASSERT_TRUE(memory->CreateAndMap(memory_size));
   scoped_ptr<DiscardableSharedMemoryHeap::Span> new_span(
-      heap.Grow(memory.Pass(), memory_size));
+      heap.Grow(memory.Pass(), memory_size, base::Bind(NullTask)));
 
   // Split span into two.
   scoped_ptr<DiscardableSharedMemoryHeap::Span> leftover =
@@ -152,7 +156,8 @@ TEST(DiscardableSharedMemoryHeapTest, Grow) {
   scoped_ptr<base::DiscardableSharedMemory> memory1(
       new base::DiscardableSharedMemory);
   ASSERT_TRUE(memory1->CreateAndMap(block_size));
-  heap.MergeIntoFreeLists(heap.Grow(memory1.Pass(), block_size).Pass());
+  heap.MergeIntoFreeLists(
+      heap.Grow(memory1.Pass(), block_size, base::Bind(NullTask)).Pass());
 
   // Remove a span from free lists.
   scoped_ptr<DiscardableSharedMemoryHeap::Span> span1 =
@@ -166,7 +171,8 @@ TEST(DiscardableSharedMemoryHeapTest, Grow) {
   scoped_ptr<base::DiscardableSharedMemory> memory2(
       new base::DiscardableSharedMemory);
   ASSERT_TRUE(memory2->CreateAndMap(block_size));
-  heap.MergeIntoFreeLists(heap.Grow(memory2.Pass(), block_size).Pass());
+  heap.MergeIntoFreeLists(
+      heap.Grow(memory2.Pass(), block_size, base::Bind(NullTask)).Pass());
 
   // Memory should now be available.
   scoped_ptr<DiscardableSharedMemoryHeap::Span> span2 =
@@ -186,7 +192,7 @@ TEST(DiscardableSharedMemoryHeapTest, ReleaseFreeMemory) {
       new base::DiscardableSharedMemory);
   ASSERT_TRUE(memory->CreateAndMap(block_size));
   scoped_ptr<DiscardableSharedMemoryHeap::Span> span =
-      heap.Grow(memory.Pass(), block_size);
+      heap.Grow(memory.Pass(), block_size, base::Bind(NullTask));
 
   // Free lists should be empty.
   EXPECT_EQ(0u, heap.GetSizeOfFreeLists());
@@ -212,7 +218,7 @@ TEST(DiscardableSharedMemoryHeapTest, ReleasePurgedMemory) {
       new base::DiscardableSharedMemory);
   ASSERT_TRUE(memory->CreateAndMap(block_size));
   scoped_ptr<DiscardableSharedMemoryHeap::Span> span =
-      heap.Grow(memory.Pass(), block_size);
+      heap.Grow(memory.Pass(), block_size, base::Bind(NullTask));
 
   // Unlock memory so it can be purged.
   span->shared_memory()->Unlock(0, 0);
@@ -239,7 +245,8 @@ TEST(DiscardableSharedMemoryHeapTest, Slack) {
   scoped_ptr<base::DiscardableSharedMemory> memory(
       new base::DiscardableSharedMemory);
   ASSERT_TRUE(memory->CreateAndMap(memory_size));
-  heap.MergeIntoFreeLists(heap.Grow(memory.Pass(), memory_size).Pass());
+  heap.MergeIntoFreeLists(
+      heap.Grow(memory.Pass(), memory_size, base::Bind(NullTask)).Pass());
 
   // No free span that is less or equal to 3 + 1.
   EXPECT_FALSE(heap.SearchFreeLists(3, 1));
@@ -257,5 +264,27 @@ TEST(DiscardableSharedMemoryHeapTest, Slack) {
   heap.MergeIntoFreeLists(span.Pass());
 }
 
+void OnDeleted(bool* deleted) {
+  *deleted = true;
+}
+
+TEST(DiscardableSharedMemoryHeapTest, DeletedCallback) {
+  size_t block_size = base::GetPageSize();
+  DiscardableSharedMemoryHeap heap(block_size);
+
+  scoped_ptr<base::DiscardableSharedMemory> memory(
+      new base::DiscardableSharedMemory);
+  ASSERT_TRUE(memory->CreateAndMap(block_size));
+  bool deleted = false;
+  scoped_ptr<DiscardableSharedMemoryHeap::Span> span =
+      heap.Grow(memory.Pass(), block_size,
+                base::Bind(OnDeleted, base::Unretained(&deleted)));
+
+  heap.MergeIntoFreeLists(span.Pass());
+  heap.ReleaseFreeMemory();
+
+  EXPECT_TRUE(deleted);
+}
+
 }  // namespace
 }  // namespace content