Add MemoryWedge to ios/.

ios/chrome/browser/experimental_flags.mm

 // 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.
 
 // This file can be empty. Its purpose is to contain the relatively short lived
 // definitions required for experimental flags.
 
 #include "ios/chrome/browser/experimental_flags.h"
 
+#include <string>
+
 #include "base/command_line.h"
+#include "base/metrics/field_trial.h"
+#include "base/strings/string_number_conversions.h"
+#include "components/variations/variations_associated_data.h"
 #include "ios/chrome/browser/chrome_switches.h"
 
 namespace experimental_flags {
 
 bool IsOpenFromClipboardEnabled() {
   base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
   return command_line->HasSwitch(switches::kEnableIOSOpenFromClipboard);
 }
 
+size_t MemoryWedgeSizeInMB() {
+  std::string wedge_size_string;
+
+  // Get the size from the Experimental setting.
+  base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
+  wedge_size_string =
+      command_line->GetSwitchValueASCII(switches::kIOSMemoryWedgeSize);
+
+  // Otherwise, get from a variation param.
+  if (wedge_size_string.empty()) {
+    wedge_size_string =
+        variations::GetVariationParamValue("MemoryWedge", "wedge_size");
+  }
+
+  // Parse the value.
+  size_t wedge_size_in_mb = 0;
+  if (base::StringToSizeT(wedge_size_string, &wedge_size_in_mb))
+    return wedge_size_in_mb;
+  return 0;
+}
+
 }  // namespace experimental_flags