Add AwDataReductionProxyManager

android_webview/java/src/org/chromium/android_webview/AwDataReductionProxyManager.java

Index: android_webview/java/src/org/chromium/android_webview/AwDataReductionProxyManager.java
diff --git a/android_webview/java/src/org/chromium/android_webview/AwDataReductionProxyManager.java b/android_webview/java/src/org/chromium/android_webview/AwDataReductionProxyManager.java
new file mode 100644
index 0000000000000000000000000000000000000000..75e6e68b5a4d114b1eec1357855adb587531907e
--- /dev/null
+++ b/android_webview/java/src/org/chromium/android_webview/AwDataReductionProxyManager.java
@@ -0,0 +1,156 @@
+// 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.
+
+package org.chromium.android_webview;
+
+import android.content.ContentResolver;
+import android.content.Context;
+import android.database.ContentObserver;
+import android.database.Cursor;
+import android.database.SQLException;
+import android.net.Uri;
+import android.os.AsyncTask;
+import android.os.Handler;
+import android.util.Log;
+
+import org.chromium.base.CommandLine;
+
+import java.lang.reflect.Field;
+
+/**
+ * Controls data reduction proxy.
+ */
+public final class AwDataReductionProxyManager {
+    // The setting Uri. Used when querying GoogleSettings.
+    // TODO: This GoogleSettings Uri does not exist yet!
+    private static final Uri CONTENT_URI = Uri.parse("content://com.google.settings/partner");
+
+    // Setting name for allowing data reduction proxy. Used when querying GoogleSettings.
+    // Setting type: int ( 0 = disallow, 1 = allow )
+    private static final String WEBVIEW_DATA_REDUCTION_PROXY = "use_webview_data_reduction_proxy";
+
+    private static final String DRP_CLASS = "com.android.webview.chromium.Drp";
+    private static final String TAG = "DataReductionProxySettingListener";
+
+    // This is the same as Chromium data_reduction_proxy::switches::kEnableDataReductionProxy.
+    private static final String ENABLE_DATA_REDUCTION_PROXY = "enable-spdy-proxy-auth";
+    // This is the same as Chromium data_reduction_proxy::switches::kDataReductionProxyKey.
+    private static final String DATA_REDUCTION_PROXY_KEY = "spdy-proxy-auth-value";
+
+    private ContentObserver mProxySettingObserver;
+
+    public AwDataReductionProxyManager() {}
+
+    public void start(final Context context) {
+        // This is the DRP key embedded in WebView apk.
+        final String embeddedKey = readKey();
+
+        // Developers could test DRP by passing ENABLE_DATA_REDUCTION_PROXY and (optionally)
+        // DATA_REDUCTION_PROXY_KEY to the commandline switches.  In this case, we will try to
+        // initialize DRP from commandline. And ignore user's preference.  If
+        // DATA_REDUCTION_PROXY_KEY is specified in commandline, use it.  Otherwise, use the key
+        // embedded in WebView apk.
+        CommandLine cl = CommandLine.getInstance();
+        if (cl.hasSwitch(ENABLE_DATA_REDUCTION_PROXY)) {
+            String key = cl.getSwitchValue(DATA_REDUCTION_PROXY_KEY, embeddedKey);
+            if (key == null || key.isEmpty()) {
+                return;
+            }
+
+            // Now we will enable DRP because we've got a commandline switch to enable it.
+            // We won't listen to Google Settings preference change because commandline switches
+            // trump that.
+            AwContentsStatics.setDataReductionProxyKey(key);
+            AwContentsStatics.setDataReductionProxyEnabled(true);
+            return;
+        }
+
+        // Now, there is no commandline switches to enable DRP, and reading the
+        // DRP key from WebView apk failed. Just return and leave DRP disabled.
+        if (embeddedKey == null || embeddedKey.isEmpty()) {
+            return;
+        }
+
+        applyDataReductionProxySettingsAsync(context, embeddedKey);
+        ContentResolver resolver = context.getContentResolver();
+        mProxySettingObserver = new ContentObserver(new Handler()) {
+            @Override
+            public void onChange(boolean selfChange, Uri uri) {
+                applyDataReductionProxySettingsAsync(context, embeddedKey);
+            }
+        };
+        resolver.registerContentObserver(
+                Uri.withAppendedPath(CONTENT_URI, WEBVIEW_DATA_REDUCTION_PROXY), false,
+                mProxySettingObserver);
+    }
+
+    private String readKey() {
+        try {
+            Class<?> cls = Class.forName(DRP_CLASS);
+            Field f = cls.getField("KEY");
+            return (String) f.get(null);
+        } catch (ClassNotFoundException ex) {
+            Log.e(TAG, "No DRP key due to exception:" + ex);
+        } catch (NoSuchFieldException ex) {
+            Log.e(TAG, "No DRP key due to exception:" + ex);
+        } catch (SecurityException ex) {
+            Log.e(TAG, "No DRP key due to exception:" + ex);
+        } catch (IllegalArgumentException ex) {
+            Log.e(TAG, "No DRP key due to exception:" + ex);
+        } catch (IllegalAccessException ex) {
+            Log.e(TAG, "No DRP key due to exception:" + ex);
+        } catch (NullPointerException ex) {
+            Log.e(TAG, "No DRP key due to exception:" + ex);
+        }
+        return null;
+    }
+
+    private static void applyDataReductionProxySettingsAsync(
+            final Context context, final String key) {
+        AsyncTask<Void, Void, Boolean> task = new AsyncTask<Void, Void, Boolean>() {
+            @Override
+            protected Boolean doInBackground(Void... params) {
+                return isDataReductionProxyEnabled(context);
+            }
+            @Override
+            protected void onPostExecute(Boolean enabled) {
+                if (enabled) {
+                    // Set the data reduction proxy key.
+                    AwContentsStatics.setDataReductionProxyKey(key);
+                }
+                AwContentsStatics.setDataReductionProxyEnabled(enabled);
+            }
+        };
+        task.execute();
+    }
+
+    private static boolean isDataReductionProxyEnabled(Context context) {
+        return getProxySetting(context.getContentResolver(), WEBVIEW_DATA_REDUCTION_PROXY) != 0;
+    }
+
+    // Read query setting from GoogleSettings.
+    private static int getProxySetting(ContentResolver resolver, String name) {
+        String value = null;
+        Cursor c = null;
+        try {
+            c = resolver.query(
+                    CONTENT_URI, new String[] {"value"}, "name=?", new String[] {name}, null);
+            if (c != null && c.moveToNext()) value = c.getString(0);
+        } catch (SQLException e) {
+            // SQL error: return null, but don't cache it.
+            Log.e(TAG, "Can't get key " + name + " from " + CONTENT_URI, e);
+        } finally {
+            if (c != null) c.close();
+        }
+        int enabled = 0;
+        try {
+            if (value != null) {
+                enabled = Integer.parseInt(value);
+            }
+        } catch (NumberFormatException e) {
+            Log.e(TAG, "cannot parse" + value, e);
+        }
+        return enabled;
+    }
+}