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

content/renderer/render_thread_impl_browsertest.cc

 // Copyright 2013 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 "base/command_line.h"
+#include "base/memory/discardable_memory.h"
+#include "base/memory/discardable_memory_emulated.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"
 #include "content/public/renderer/content_renderer_client.h"
 #include "content/renderer/render_process_impl.h"
 #include "content/renderer/render_thread_impl.h"
 #include "content/test/mock_render_process.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace content {
@@ skipping 47 matching lines @@
   RenderThreadImpl* thread = new RenderThreadImpl(channel_id);
   thread->EnsureWebKitInitialized();
 
   ASSERT_TRUE(thread->input_handler_manager());
 
   thread->compositor_message_loop_proxy()->PostTask(
       FROM_HERE,
       base::Bind(&CheckRenderThreadInputHandlerManager, thread));
 }
 
+// Checks that emulated discardable memory is discarded when the last widget
+// is hidden.
+TEST_F(RenderThreadImplBrowserTest,
+       DiscardableMemoryDiscardedWhenWidgetsHidden) {
+  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();
+
+  base::DiscardableMemoryEmulated::SetModeratePressureLimit(4 * 1024 * 1024);
+
+  // 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