Add a DiscardableMemoryShmemeAllocator.

mojo/services/html_viewer/html_viewer_discardable_memory_shmem_allocator.h

Index: mojo/services/html_viewer/html_viewer_discardable_memory_shmem_allocator.h
diff --git a/mojo/services/html_viewer/html_viewer_discardable_memory_shmem_allocator.h b/mojo/services/html_viewer/html_viewer_discardable_memory_shmem_allocator.h
new file mode 100644
index 0000000000000000000000000000000000000000..70b0b3390090d50aa988a8570f1c2f361ddaa3c8
--- /dev/null
+++ b/mojo/services/html_viewer/html_viewer_discardable_memory_shmem_allocator.h
@@ -0,0 +1,31 @@
+// Copyright 2015 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.
+
+#ifndef MOJO_SERVICES_HTML_VIEWER_HTML_VIEWER_DISCARDABLE_MEMORY_SHMEM_ALLOCATOR_H_
+#define MOJO_SERVICES_HTML_VIEWER_HTML_VIEWER_DISCARDABLE_MEMORY_SHMEM_ALLOCATOR_H_
+
+#include "base/memory/discardable_memory_shmem_allocator.h"
+
+namespace html_viewer {
+
+// This is a copy of the testing allocator, which doesn't actually do any

[jamesr, 2015/03/16 23:47:25]

statements about history are not very useful in comments and likely to go stale
immediately. they're far more useful in the patch description. please describe
what this class does in the header, not where it's from

+// tricks with shared memory. It is the minimal interface needed to get a
+// Google search working in the html viewer.
+class HtmlViewerDiscardableMemoryShmemAllocator

[jamesr, 2015/03/16 23:47:25]

you're in the directory html_viewer and in the namespace html_viewer so
repeating "HtmlViewer" in the class name only makes this class name really long
without adding any information. please shorten it up to describe what it does

+    : public base::DiscardableMemoryShmemAllocator {
+ public:
+  HtmlViewerDiscardableMemoryShmemAllocator();
+  ~HtmlViewerDiscardableMemoryShmemAllocator() override;
+
+  // Overridden from DiscardableMemoryShmemAllocator:
+  scoped_ptr<base::DiscardableMemoryShmemChunk> AllocateLockedDiscardableMemory(
+      size_t size) override;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(HtmlViewerDiscardableMemoryShmemAllocator);
+};
+
+}  // namespace html_viewer
+
+#endif  // MOJO_SERVICES_HTML_VIEWER_HTML_VIEWER_DISCARDABLE_MEMORY_SHMEM_ALLOCATOR_H_