android: Make org.chromium.base.SysUtils.isLowEndDevice() work without native code.

content/common/android/linker/linker_jni.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.
 
 // This is the Android-specific content linker, a tiny shared library
 // implementing a custom dynamic linker that can be used to load the
 // real content-based libraries (e.g. libcontentshell.so).
 
 // The main point of this linker is to be able to share the RELRO
 // section of libcontentshell.so (or equivalent) between the browser and
 // renderer process.
 
 // This source code *cannot* depend on anything from base/ or the C++
 // STL, to keep the final library small, and avoid ugly dependency issues.
 
 #include <android/log.h>
 #include <crazy_linker.h>
 #include <jni.h>
 #include <stdlib.h>
 #include <unistd.h>
 
-// Any device that reports a physical RAM size less than this, in megabytes
-// is considered 'low-end'. IMPORTANT: Read the LinkerLowMemoryThresholdTest
-// comments in build/android/pylib/linker/test_case.py before modifying this
-// value.
-#define ANDROID_LOW_MEMORY_DEVICE_THRESHOLD_MB 512
-
 // Set this to 1 to enable debug traces to the Android log.
 // Note that LOG() from "base/logging.h" cannot be used, since it is
 // in base/ which hasn't been loaded yet.
 #define DEBUG 0
 
 #define TAG "content_android_linker"
 
 #if DEBUG
 #define LOG_INFO(...) __android_log_print(ANDROID_LOG_INFO, TAG, __VA_ARGS__)
 #define LOG_ERROR(...) __android_log_print(ANDROID_LOG_ERROR, TAG, __VA_ARGS__)
@@ skipping 343 matching lines @@
 jboolean CanUseSharedRelro(JNIEnv* env, jclass clazz) {
   return crazy_system_can_share_relro();
 }
 
 jlong GetPageSize(JNIEnv* env, jclass clazz) {
   jlong result = static_cast<jlong>(sysconf(_SC_PAGESIZE));
   LOG_INFO("%s: System page size is %lld bytes\n", __FUNCTION__, result);
   return result;
 }
 
-jboolean IsLowMemoryDevice(JNIEnv* env, jclass clazz) {
-  // This matches the implementation of org.chromium.base.SysUtils.isLowEnd(),
-  // however this Java method relies on native code from base/, which isn't
-  // available since the library hasn't been loaded yet.
-  // The value ANDROID_LOW_MEMORY_DEVICE_THRESHOLD_MB is the same for both
-  // sources.
-
-  // Threshold for low-end memory devices.
-  const size_t kMegaBytes = 1024 * 1024;
-  const size_t kLowMemoryDeviceThreshold =
-      ANDROID_LOW_MEMORY_DEVICE_THRESHOLD_MB * kMegaBytes;
-
-  // Compute the amount of physical RAM on the device.
-  size_t pages = static_cast<size_t>(sysconf(_SC_PHYS_PAGES));
-  size_t page_size = static_cast<size_t>(sysconf(_SC_PAGESIZE));
-  size_t physical_size = pages * page_size;
-
-  LOG_INFO("%s: System physical size is %zu MB\n",
-           __FUNCTION__,
-           physical_size / kMegaBytes);
-
-  return physical_size <= kLowMemoryDeviceThreshold;
-}
-
 const JNINativeMethod kNativeMethods[] = {
     {"nativeLoadLibrary",
      "("
      "Ljava/lang/String;"
      "J"
      "Lorg/chromium/content/app/Linker$LibInfo;"
      ")"
      "Z",
      reinterpret_cast<void*>(&LoadLibrary)},
     {"nativeCreateSharedRelro",
@@ skipping 13 matching lines @@
      reinterpret_cast<void*>(&UseSharedRelro)},
     {"nativeCanUseSharedRelro",
      "("
      ")"
      "Z",
      reinterpret_cast<void*>(&CanUseSharedRelro)},
     {"nativeGetPageSize",
      "("
      ")"
      "J",
-     reinterpret_cast<void*>(&GetPageSize)},
-    {"nativeIsLowMemoryDevice",
-     "("
-     ")"
-     "Z",
-     reinterpret_cast<void*>(&IsLowMemoryDevice)}, };
+     reinterpret_cast<void*>(&GetPageSize)}, };
 
 }  // namespace
 
 // JNI_OnLoad() hook called when the linker library is loaded through
 // the regular System.LoadLibrary) API. This shall save the Java VM
 // handle and initialize LibInfo fields.
 jint JNI_OnLoad(JavaVM* vm, void* reserved) {
   LOG_INFO("%s: Entering", __FUNCTION__);
   // Get new JNIEnv
   JNIEnv* env;
@@ skipping 19 matching lines @@
     return -1;
   }
 
   // Save JavaVM* handle into context.
   crazy_context_t* context = GetCrazyContext();
   crazy_context_set_java_vm(context, vm, JNI_VERSION_1_4);
 
   LOG_INFO("%s: Done", __FUNCTION__);
   return JNI_VERSION_1_4;
 }