Changing OOM range to 0, 1000 and tweaking OOM algorithm.

content/browser/zygote_host_linux.h

 // Copyright (c) 2011 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 CONTENT_BROWSER_ZYGOTE_HOST_LINUX_H_
 #define CONTENT_BROWSER_ZYGOTE_HOST_LINUX_H_
 #pragma once
 
 #include <unistd.h>
 
@@ skipping 56 matching lines @@
   pid_t pid() const { return pid_; }
 
   // Returns an int which is a bitmask of kSandbox* values. Only valid after
   // the first render has been forked.
   int sandbox_status() const {
     if (have_read_sandbox_status_word_)
       return sandbox_status_;
     return 0;
   }
 
-  // Adjust the OOM score of the given renderer's PID.
+  // Adjust the OOM score of the given renderer's PID.  The allowed
+  // range for the score is [0, 1000], where higher values are more
+  // likely to be killed by the OOM killer.
   void AdjustRendererOOMScore(base::ProcessHandle process_handle, int score);
 
  private:
   friend struct DefaultSingletonTraits<ZygoteHost>;
   ZygoteHost();
   ~ZygoteHost();
 
   ssize_t ReadReply(void* buf, size_t buflen);
 
   int control_fd_;  // the socket to the zygote
   // A lock protecting all communication with the zygote. This lock must be
   // acquired before sending a command and released after the result has been
   // received.
   base::Lock control_lock_;
   pid_t pid_;
   bool init_;
   bool using_suid_sandbox_;
   std::string sandbox_binary_;
   bool have_read_sandbox_status_word_;
   int sandbox_status_;
 };
 
 #endif  // CONTENT_BROWSER_ZYGOTE_HOST_LINUX_H_