Re-land: base: Introduce an explicit call for reducing emulated discardable memory usage.

content/renderer/render_thread_impl_browsertest.cc

Index: content/renderer/render_thread_impl_browsertest.cc
diff --git a/content/renderer/render_thread_impl_browsertest.cc b/content/renderer/render_thread_impl_browsertest.cc
index f5a0d1d7f7df750f26ae6beba93868d40690dcfd..099da86004b9445a39a15722927633423d1a2274 100644
--- a/content/renderer/render_thread_impl_browsertest.cc
+++ b/content/renderer/render_thread_impl_browsertest.cc
@@ -3,6 +3,8 @@
 // found in the LICENSE file.
 
 #include "base/command_line.h"
+#include "base/memory/discardable_memory.h"
+#include "base/memory/scoped_vector.h"
 #include "content/public/browser/content_browser_client.h"
 #include "content/public/common/content_client.h"
 #include "content/public/common/content_switches.h"
@@ -70,5 +72,63 @@ TEST_F(RenderThreadImplBrowserTest,
       base::Bind(&CheckRenderThreadInputHandlerManager, thread));
 }
 
+// Checks that emulated discardable memory is discarded when the last widget
+// is hidden.
+// Disabled under LeakSanitizer due to memory leaks.
+#if defined(LEAK_SANITIZER)
+#define MAYBE_EmulatedDiscardableMemoryDiscardedWhenWidgetsHidden \
+  DISABLED_EmulatedDiscardableMemoryDiscardedWhenWidgetsHidden
+#else
+#define MAYBE_EmulatedDiscardableMemoryDiscardedWhenWidgetsHidden \
+  EmulatedDiscardableMemoryDiscardedWhenWidgetsHidden
+#endif
+TEST_F(RenderThreadImplBrowserTest,
+       MAYBE_EmulatedDiscardableMemoryDiscardedWhenWidgetsHidden) {
+  ContentClient content_client;
+  ContentBrowserClient content_browser_client;
+  ContentRendererClient content_renderer_client;
+  SetContentClient(&content_client);
+  SetBrowserClientForTesting(&content_browser_client);
+  SetRendererClientForTesting(&content_renderer_client);
+  base::MessageLoopForIO message_loop_;
+
+  std::string channel_id =
+      IPC::Channel::GenerateVerifiedChannelID(std::string());
+  DummyListener dummy_listener;
+  scoped_ptr<IPC::Channel> channel(
+      IPC::Channel::CreateServer(channel_id, &dummy_listener));
+  ASSERT_TRUE(channel->Connect());
+
+  scoped_ptr<MockRenderProcess> mock_process(new MockRenderProcess);
+  // Owned by mock_process.
+  RenderThreadImpl* thread = new RenderThreadImpl(channel_id);
+  thread->EnsureWebKitInitialized();
+  thread->WidgetCreated();
+
+  // Allocate 128MB of discardable memory.
+  ScopedVector<base::DiscardableMemory> discardable_memory;
+  for (int i = 0; i < 32; ++i) {
+    discardable_memory.push_back(
+        base::DiscardableMemory::CreateLockedMemoryWithType(
+            base::DISCARDABLE_MEMORY_TYPE_EMULATED, 4 * 1024 * 1024).release());
+    ASSERT_TRUE(discardable_memory.back());
+    discardable_memory.back()->Unlock();
+  }
+
+  // Hide all widgets.
+  thread->WidgetHidden();
+
+  // Count how much memory is left, should be at most one block.
+  int blocks_left = 0;
+  for (auto iter = discardable_memory.begin(); iter != discardable_memory.end();
+       ++iter) {
+    if ((*iter)->Lock() == base::DISCARDABLE_MEMORY_LOCK_STATUS_SUCCESS)
+      ++blocks_left;
+  }
+  EXPECT_LE(blocks_left, 1);
+
+  thread->WidgetDestroyed();
+}
+
 }  // namespace
 }  // namespace content