[Android WebView] Fix thread unsafety in accessing Java side getters

android_webview/java/src/org/chromium/android_webview/AwSettings.java

 // Copyright 2012 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.Context;
 import android.content.pm.PackageManager;
 import android.os.Handler;
 import android.os.Message;
@@ skipping 113 matching lines @@
     // Custom handler that queues messages to call native code on the UI thread.
     private final EventHandler mEventHandler;
 
     private static final int MINIMUM_FONT_SIZE = 1;
     private static final int MAXIMUM_FONT_SIZE = 72;
 
     // Class to handle messages to be processed on the UI thread.
     private class EventHandler {
         // Message id for updating Webkit preferences
         private static final int UPDATE_WEBKIT_PREFERENCES = 0;
+        // Message id for running a Runnable

[benm (inactive), 2014/01/24 02:20:21]

nit: ... with the AwSettingsLock held.

[mnaganov (inactive), 2014/01/24 10:01:47]

Done.

+        private static final int RUN_RUNNABLE_BLOCKING = 1;
         // Actual UI thread handler
         private Handler mHandler;
 
         EventHandler() {
         }
 
         void bindUiThread() {
             if (mHandler != null) return;
             mHandler = new Handler(ThreadUtils.getUiThreadLooper()) {
                 @Override
                 public void handleMessage(Message msg) {
                     switch (msg.what) {
                         case UPDATE_WEBKIT_PREFERENCES:
                             synchronized (mAwSettingsLock) {
                                 updateWebkitPreferencesOnUiThreadLocked();
                                 mIsUpdateWebkitPrefsMessagePending = false;
                                 mAwSettingsLock.notifyAll();
                             }
                             break;
+                        case RUN_RUNNABLE_BLOCKING:
+                            synchronized (mAwSettingsLock) {
+                                ((Runnable)msg.obj).run();
+                                mAwSettingsLock.notifyAll();
+                            }
+                            break;
                     }
                 }
             };
         }
 
         void maybeRunOnUiThreadBlocking(Runnable r) {
-            if (mHandler != null) {
-                ThreadUtils.runOnUiThreadBlocking(r);
+            assert Thread.holdsLock(mAwSettingsLock);
+            if (mHandler == null) return;
+            if (ThreadUtils.runningOnUiThread()) {
+                r.run();
+            } else {
+                mHandler.sendMessage(Message.obtain(null, RUN_RUNNABLE_BLOCKING, r));
+                try {
+                    mAwSettingsLock.wait();

[benm (inactive), 2014/01/24 02:20:21]

shouldn't we have this in a while loop and set a bit when the runnable executes
in the handler above?

[mnaganov (inactive), 2014/01/24 10:01:47]

Ah, of course! Even better -- fixing this makes updateWebkitPreferencesLocked to
be a special case of maybeRunOnUiThreadBlocking. Since we sync to native
synchronously after each preference change, the role of
mIsUpdateWebkitPrefsMessagePending to prevent sending superfluous messages is
obsolete -- it is only used for syncing between threads. So I can throw away
some duplicate code!

+                } catch (InterruptedException e) {
+                    Log.e(TAG, "Interrupted waiting a Runnable to complete", e);
+                }
             }
         }
 
         void maybePostOnUiThread(Runnable r) {
             if (mHandler != null) {
                 mHandler.post(r);
             }
         }
 
         private void updateWebkitPreferencesLocked() {
@@ skipping 60 matching lines @@
     }
 
     @CalledByNative
     private void nativeAwSettingsGone(long nativeAwSettings) {
         assert mNativeAwSettings != 0 && mNativeAwSettings == nativeAwSettings;
         mNativeAwSettings = 0;
     }
 
     @CalledByNative
     private double getDIPScaleLocked() {
+        assert Thread.holdsLock(mAwSettingsLock);
         return mDIPScale;
     }
 
     void setDIPScale(double dipScale) {
         synchronized (mAwSettingsLock) {
             mDIPScale = dipScale;
             // TODO(joth): This should also be synced over to native side, but right now
             // the setDIPScale call is always followed by a setWebContents() which covers this.
         }
     }
@@ skipping 124 matching lines @@
                             nativeUpdateInitialPageScaleLocked(mNativeAwSettings);
                         }
                     }
                 });
             }
         }
     }
 
     @CalledByNative
     private float getInitialPageScalePercentLocked() {
+        assert Thread.holdsLock(mAwSettingsLock);
         return mInitialPageScalePercent;
     }
 
     void setSpatialNavigationEnabled(boolean enable) {
         synchronized (mAwSettingsLock) {
             if (mSpatialNavigationEnabled != enable) {
                 mSpatialNavigationEnabled = enable;
                 mEventHandler.updateWebkitPreferencesLocked();
             }
         }
     }
 
     @CalledByNative
     private boolean getSpatialNavigationLocked() {
+        assert Thread.holdsLock(mAwSettingsLock);
         return mSpatialNavigationEnabled;
     }
 
     void setEnableSupportedHardwareAcceleratedFeatures(boolean enable) {
         synchronized (mAwSettingsLock) {
             if (mEnableSupportedHardwareAcceleratedFeatures != enable) {
                 mEnableSupportedHardwareAcceleratedFeatures = enable;
                 mEventHandler.updateWebkitPreferencesLocked();
             }
         }
     }
 
     @CalledByNative
     private boolean getEnableSupportedHardwareAcceleratedFeaturesLocked() {
+        assert Thread.holdsLock(mAwSettingsLock);
         return mEnableSupportedHardwareAcceleratedFeatures;
     }
 
     /**
      * See {@link android.webkit.WebSettings#setNeedInitialFocus}.
      */
     public boolean shouldFocusFirstNode() {
         synchronized (mAwSettingsLock) {
             return mShouldFocusFirstNode;
         }
@@ skipping 42 matching lines @@
      * See {@link android.webkit.WebSettings#getSaveFormData}.
      */
     public boolean getSaveFormData() {
         synchronized (mAwSettingsLock) {
             return getSaveFormDataLocked();
         }
     }
 
     @CalledByNative
     private boolean getSaveFormDataLocked() {
+        assert Thread.holdsLock(mAwSettingsLock);
         return mAutoCompleteEnabled;
     }
 
     /**
      * @returns the default User-Agent used by each ContentViewCore instance, i.e. unless
      * overridden by {@link #setUserAgentString()}
      */
     public static String getDefaultUserAgent() {
         return LazyDefaultUserAgent.sInstance;
     }
@@ skipping 26 matching lines @@
      * See {@link android.webkit.WebSettings#getUserAgentString}.
      */
     public String getUserAgentString() {
         synchronized (mAwSettingsLock) {
             return mUserAgent;
         }
     }
 
     @CalledByNative
     private String getUserAgentLocked() {
+        assert Thread.holdsLock(mAwSettingsLock);
         return mUserAgent;
     }
 
     /**
      * See {@link android.webkit.WebSettings#setLoadWithOverviewMode}.
      */
     public void setLoadWithOverviewMode(boolean overview) {
         synchronized (mAwSettingsLock) {
             if (mLoadWithOverviewMode != overview) {
                 mLoadWithOverviewMode = overview;
@@ skipping 14 matching lines @@
      * See {@link android.webkit.WebSettings#getLoadWithOverviewMode}.
      */
     public boolean getLoadWithOverviewMode() {
         synchronized (mAwSettingsLock) {
             return mLoadWithOverviewMode;
         }
     }
 
     @CalledByNative
     private boolean getLoadWithOverviewModeLocked() {
+        assert Thread.holdsLock(mAwSettingsLock);
         return mLoadWithOverviewMode;
     }
 
     /**
      * See {@link android.webkit.WebSettings#setTextZoom}.
      */
     public void setTextZoom(final int textZoom) {
         synchronized (mAwSettingsLock) {
             int scaledTextZoomPercent = (int)(textZoom * mFontScale);
             if (mTextSizePercent != scaledTextZoomPercent) {
                 mTextSizePercent = scaledTextZoomPercent;
                 mEventHandler.updateWebkitPreferencesLocked();
             }
         }
     }
 
     /**
      * See {@link android.webkit.WebSettings#getTextZoom}.
      */
     public int getTextZoom() {
         synchronized (mAwSettingsLock) {
             return mTextSizePercent;
         }
     }
 
     @CalledByNative
     private int getTextSizePercentLocked() {
+        assert Thread.holdsLock(mAwSettingsLock);
         return mTextSizePercent;
     }
 
     /**
      * See {@link android.webkit.WebSettings#setStandardFontFamily}.
      */
     public void setStandardFontFamily(String font) {
         synchronized (mAwSettingsLock) {
             if (font != null && !mStandardFontFamily.equals(font)) {
                 mStandardFontFamily = font;
                 mEventHandler.updateWebkitPreferencesLocked();
             }
         }
     }
 
     /**
      * See {@link android.webkit.WebSettings#getStandardFontFamily}.
      */
     public String getStandardFontFamily() {
         synchronized (mAwSettingsLock) {
             return mStandardFontFamily;
         }
     }
 
     @CalledByNative
     private String getStandardFontFamilyLocked() {
+        assert Thread.holdsLock(mAwSettingsLock);
         return mStandardFontFamily;
     }
 
     /**
      * See {@link android.webkit.WebSettings#setFixedFontFamily}.
      */
     public void setFixedFontFamily(String font) {
         synchronized (mAwSettingsLock) {
             if (font != null && !mFixedFontFamily.equals(font)) {
                 mFixedFontFamily = font;
                 mEventHandler.updateWebkitPreferencesLocked();
             }
         }
     }
 
     /**
      * See {@link android.webkit.WebSettings#getFixedFontFamily}.
      */
     public String getFixedFontFamily() {
         synchronized (mAwSettingsLock) {
             return mFixedFontFamily;
         }
     }
 
     @CalledByNative
     private String getFixedFontFamilyLocked() {
+        assert Thread.holdsLock(mAwSettingsLock);
         return mFixedFontFamily;
     }
 
     /**
      * See {@link android.webkit.WebSettings#setSansSerifFontFamily}.
      */
     public void setSansSerifFontFamily(String font) {
         synchronized (mAwSettingsLock) {
             if (font != null && !mSansSerifFontFamily.equals(font)) {
                 mSansSerifFontFamily = font;
                 mEventHandler.updateWebkitPreferencesLocked();
             }
         }
     }
 
     /**
      * See {@link android.webkit.WebSettings#getSansSerifFontFamily}.
      */
     public String getSansSerifFontFamily() {
         synchronized (mAwSettingsLock) {
             return mSansSerifFontFamily;
         }
     }
 
     @CalledByNative
     private String getSansSerifFontFamilyLocked() {
+        assert Thread.holdsLock(mAwSettingsLock);
         return mSansSerifFontFamily;
     }
 
     /**
      * See {@link android.webkit.WebSettings#setSerifFontFamily}.
      */
     public void setSerifFontFamily(String font) {
         synchronized (mAwSettingsLock) {
             if (font != null && !mSerifFontFamily.equals(font)) {
                 mSerifFontFamily = font;
                 mEventHandler.updateWebkitPreferencesLocked();
             }
         }
     }
 
     /**
      * See {@link android.webkit.WebSettings#getSerifFontFamily}.
      */
     public String getSerifFontFamily() {
         synchronized (mAwSettingsLock) {
             return mSerifFontFamily;
         }
     }
 
     @CalledByNative
     private String getSerifFontFamilyLocked() {
+        assert Thread.holdsLock(mAwSettingsLock);
         return mSerifFontFamily;
     }
 
     /**
      * See {@link android.webkit.WebSettings#setCursiveFontFamily}.
      */
     public void setCursiveFontFamily(String font) {
         synchronized (mAwSettingsLock) {
             if (font != null && !mCursiveFontFamily.equals(font)) {
                 mCursiveFontFamily = font;
                 mEventHandler.updateWebkitPreferencesLocked();
             }
         }
     }
 
     /**
      * See {@link android.webkit.WebSettings#getCursiveFontFamily}.
      */
     public String getCursiveFontFamily() {
         synchronized (mAwSettingsLock) {
             return mCursiveFontFamily;
         }
     }
 
     @CalledByNative
     private String getCursiveFontFamilyLocked() {
+        assert Thread.holdsLock(mAwSettingsLock);
         return mCursiveFontFamily;
     }
 
     /**
      * See {@link android.webkit.WebSettings#setFantasyFontFamily}.
      */
     public void setFantasyFontFamily(String font) {
         synchronized (mAwSettingsLock) {
             if (font != null && !mFantasyFontFamily.equals(font)) {
                 mFantasyFontFamily = font;
                 mEventHandler.updateWebkitPreferencesLocked();
             }
         }
     }
 
     /**
      * See {@link android.webkit.WebSettings#getFantasyFontFamily}.
      */
     public String getFantasyFontFamily() {
         synchronized (mAwSettingsLock) {
             return mFantasyFontFamily;
         }
     }
 
     @CalledByNative
     private String getFantasyFontFamilyLocked() {
+        assert Thread.holdsLock(mAwSettingsLock);
         return mFantasyFontFamily;
     }
 
     /**
      * See {@link android.webkit.WebSettings#setMinimumFontSize}.
      */
     public void setMinimumFontSize(int size) {
         synchronized (mAwSettingsLock) {
             size = clipFontSize(size);
             if (mMinimumFontSize != size) {
                 mMinimumFontSize = size;
                 mEventHandler.updateWebkitPreferencesLocked();
             }
         }
     }
 
     /**
      * See {@link android.webkit.WebSettings#getMinimumFontSize}.
      */
     public int getMinimumFontSize() {
         synchronized (mAwSettingsLock) {
             return mMinimumFontSize;
         }
     }
 
     @CalledByNative
     private int getMinimumFontSizeLocked() {
+        assert Thread.holdsLock(mAwSettingsLock);
         return mMinimumFontSize;
     }
 
     /**
      * See {@link android.webkit.WebSettings#setMinimumLogicalFontSize}.
      */
     public void setMinimumLogicalFontSize(int size) {
         synchronized (mAwSettingsLock) {
             size = clipFontSize(size);
             if (mMinimumLogicalFontSize != size) {
                 mMinimumLogicalFontSize = size;
                 mEventHandler.updateWebkitPreferencesLocked();
             }
         }
     }
 
     /**
      * See {@link android.webkit.WebSettings#getMinimumLogicalFontSize}.
      */
     public int getMinimumLogicalFontSize() {
         synchronized (mAwSettingsLock) {
             return mMinimumLogicalFontSize;
         }
     }
 
     @CalledByNative
     private int getMinimumLogicalFontSizeLocked() {
+        assert Thread.holdsLock(mAwSettingsLock);
         return mMinimumLogicalFontSize;
     }
 
     /**
      * See {@link android.webkit.WebSettings#setDefaultFontSize}.
      */
     public void setDefaultFontSize(int size) {
         synchronized (mAwSettingsLock) {
             size = clipFontSize(size);
             if (mDefaultFontSize != size) {
                 mDefaultFontSize = size;
                 mEventHandler.updateWebkitPreferencesLocked();
             }
         }
     }
 
     /**
      * See {@link android.webkit.WebSettings#getDefaultFontSize}.
      */
     public int getDefaultFontSize() {
         synchronized (mAwSettingsLock) {
             return mDefaultFontSize;
         }
     }
 
     @CalledByNative
     private int getDefaultFontSizeLocked() {
+        assert Thread.holdsLock(mAwSettingsLock);
         return mDefaultFontSize;
     }
 
     /**
      * See {@link android.webkit.WebSettings#setDefaultFixedFontSize}.
      */
     public void setDefaultFixedFontSize(int size) {
         synchronized (mAwSettingsLock) {
             size = clipFontSize(size);
             if (mDefaultFixedFontSize != size) {
                 mDefaultFixedFontSize = size;
                 mEventHandler.updateWebkitPreferencesLocked();
             }
         }
     }
 
     /**
      * See {@link android.webkit.WebSettings#getDefaultFixedFontSize}.
      */
     public int getDefaultFixedFontSize() {
         synchronized (mAwSettingsLock) {
             return mDefaultFixedFontSize;
         }
     }
 
     @CalledByNative
     private int getDefaultFixedFontSizeLocked() {
+        assert Thread.holdsLock(mAwSettingsLock);
         return mDefaultFixedFontSize;
     }
 
     /**
      * See {@link android.webkit.WebSettings#setJavaScriptEnabled}.
      */
     public void setJavaScriptEnabled(boolean flag) {
         synchronized (mAwSettingsLock) {
             if (mJavaScriptEnabled != flag) {
                 mJavaScriptEnabled = flag;
@@ skipping 42 matching lines @@
      * See {@link android.webkit.WebSettings#getLoadsImagesAutomatically}.
      */
     public boolean getLoadsImagesAutomatically() {
         synchronized (mAwSettingsLock) {
             return mLoadsImagesAutomatically;
         }
     }
 
     @CalledByNative
     private boolean getLoadsImagesAutomaticallyLocked() {
+        assert Thread.holdsLock(mAwSettingsLock);
         return mLoadsImagesAutomatically;
     }
 
     /**
      * See {@link android.webkit.WebSettings#setImagesEnabled}.
      */
     public void setImagesEnabled(boolean flag) {
         synchronized (mAwSettingsLock) {
             if (mImagesEnabled != flag) {
                 mImagesEnabled = flag;
                 mEventHandler.updateWebkitPreferencesLocked();
             }
         }
     }
 
     /**
      * See {@link android.webkit.WebSettings#getImagesEnabled}.
      */
     public boolean getImagesEnabled() {
         synchronized (mAwSettingsLock) {
             return mImagesEnabled;
         }
     }
 
     @CalledByNative
     private boolean getImagesEnabledLocked() {
+        assert Thread.holdsLock(mAwSettingsLock);
         return mImagesEnabled;
     }
 
     /**
      * See {@link android.webkit.WebSettings#getJavaScriptEnabled}.
      */
     public boolean getJavaScriptEnabled() {
         synchronized (mAwSettingsLock) {
             return mJavaScriptEnabled;
         }
     }
 
     @CalledByNative
     private boolean getJavaScriptEnabledLocked() {
+        assert Thread.holdsLock(mAwSettingsLock);
         return mJavaScriptEnabled;
     }
 
     /**
      * See {@link android.webkit.WebSettings#getAllowUniversalAccessFromFileURLs}.
      */
     public boolean getAllowUniversalAccessFromFileURLs() {
         synchronized (mAwSettingsLock) {
             return mAllowUniversalAccessFromFileURLs;
         }
     }
 
     @CalledByNative
     private boolean getAllowUniversalAccessFromFileURLsLocked() {
+        assert Thread.holdsLock(mAwSettingsLock);
         return mAllowUniversalAccessFromFileURLs;
     }
 
     /**
      * See {@link android.webkit.WebSettings#getAllowFileAccessFromFileURLs}.
      */
     public boolean getAllowFileAccessFromFileURLs() {
         synchronized (mAwSettingsLock) {
             return mAllowFileAccessFromFileURLs;
         }
     }
 
     @CalledByNative
     private boolean getAllowFileAccessFromFileURLsLocked() {
+        assert Thread.holdsLock(mAwSettingsLock);
         return mAllowFileAccessFromFileURLs;
     }
 
     /**
      * See {@link android.webkit.WebSettings#setPluginsEnabled}.
      */
     public void setPluginsEnabled(boolean flag) {
         setPluginState(flag ? PluginState.ON : PluginState.OFF);
     }
 
@@ skipping 14 matching lines @@
      */
     public boolean getPluginsEnabled() {
         synchronized (mAwSettingsLock) {
             return mPluginState == PluginState.ON;
         }
     }
 
     /**
      * Return true if plugins are disabled.
      * @return True if plugins are disabled.
-     * @hide
      */
     @CalledByNative
     private boolean getPluginsDisabledLocked() {
+        assert Thread.holdsLock(mAwSettingsLock);
         return mPluginState == PluginState.OFF;
     }
 
     /**
      * See {@link android.webkit.WebSettings#getPluginState}.
      */
     public PluginState getPluginState() {
         synchronized (mAwSettingsLock) {
             return mPluginState;
         }
@@ skipping 16 matching lines @@
      * See {@link android.webkit.WebSettings#getJavaScriptCanOpenWindowsAutomatically}.
      */
     public boolean getJavaScriptCanOpenWindowsAutomatically() {
         synchronized (mAwSettingsLock) {
             return mJavaScriptCanOpenWindowsAutomatically;
         }
     }
 
     @CalledByNative
     private boolean getJavaScriptCanOpenWindowsAutomaticallyLocked() {
+        assert Thread.holdsLock(mAwSettingsLock);
         return mJavaScriptCanOpenWindowsAutomatically;
     }
 
     /**
      * See {@link android.webkit.WebSettings#setLayoutAlgorithm}.
      */
     public void setLayoutAlgorithm(LayoutAlgorithm l) {
         synchronized (mAwSettingsLock) {
             if (mLayoutAlgorithm != l) {
                 mLayoutAlgorithm = l;
                 mEventHandler.updateWebkitPreferencesLocked();
             }
         }
     }
 
     /**
      * See {@link android.webkit.WebSettings#getLayoutAlgorithm}.
      */
     public LayoutAlgorithm getLayoutAlgorithm() {
         synchronized (mAwSettingsLock) {
             return mLayoutAlgorithm;
         }
     }
 
     /**
      * Gets whether Text Auto-sizing layout algorithm is enabled.
      *
      * @return true if Text Auto-sizing layout algorithm is enabled
-     * @hide
      */
     @CalledByNative
     private boolean getTextAutosizingEnabledLocked() {
+        assert Thread.holdsLock(mAwSettingsLock);
         return mLayoutAlgorithm == LayoutAlgorithm.TEXT_AUTOSIZING;
     }
 
     /**
      * See {@link android.webkit.WebSettings#setSupportMultipleWindows}.
      */
     public void setSupportMultipleWindows(boolean support) {
         synchronized (mAwSettingsLock) {
             if (mSupportMultipleWindows != support) {
                 mSupportMultipleWindows = support;
                 mEventHandler.updateWebkitPreferencesLocked();
             }
         }
     }
 
     /**
      * See {@link android.webkit.WebSettings#supportMultipleWindows}.
      */
     public boolean supportMultipleWindows() {
         synchronized (mAwSettingsLock) {
             return mSupportMultipleWindows;
         }
     }
 
     @CalledByNative
     private boolean getSupportMultipleWindowsLocked() {
+        assert Thread.holdsLock(mAwSettingsLock);
         return mSupportMultipleWindows;
     }
 
     @CalledByNative
     private boolean getSupportLegacyQuirksLocked() {
+        assert Thread.holdsLock(mAwSettingsLock);
         return mSupportLegacyQuirks;
     }
 
     /**
      * See {@link android.webkit.WebSettings#setUseWideViewPort}.
      */
     public void setUseWideViewPort(boolean use) {
         synchronized (mAwSettingsLock) {
             if (mUseWideViewport != use) {
                 mUseWideViewport = use;
                 mEventHandler.updateWebkitPreferencesLocked();
             }
         }
     }
 
     /**
      * See {@link android.webkit.WebSettings#getUseWideViewPort}.
      */
     public boolean getUseWideViewPort() {
         synchronized (mAwSettingsLock) {
             return mUseWideViewport;
         }
     }
 
     @CalledByNative
     private boolean getUseWideViewportLocked() {
+        assert Thread.holdsLock(mAwSettingsLock);
         return mUseWideViewport;
     }
 
     @CalledByNative
     private boolean getPasswordEchoEnabledLocked() {
+        assert Thread.holdsLock(mAwSettingsLock);
         return mPasswordEchoEnabled;
     }
 
     /**
      * See {@link android.webkit.WebSettings#setAppCacheEnabled}.
      */
     public void setAppCacheEnabled(boolean flag) {
         synchronized (mAwSettingsLock) {
             if (mAppCacheEnabled != flag) {
                 mAppCacheEnabled = flag;
@@ skipping 21 matching lines @@
             synchronized (mAwSettingsLock) {
                 mEventHandler.updateWebkitPreferencesLocked();
             }
         }
     }
 
     /**
      * Gets whether Application Cache is enabled.
      *
      * @return true if Application Cache is enabled
-     * @hide
      */
     @CalledByNative
     private boolean getAppCacheEnabledLocked() {
+        assert Thread.holdsLock(mAwSettingsLock);
         if (!mAppCacheEnabled) {
             return false;
         }
         synchronized (sGlobalContentSettingsLock) {
             return sAppCachePathIsSet;
         }
     }
 
     /**
      * See {@link android.webkit.WebSettings#setDomStorageEnabled}.
@@ skipping 11 matching lines @@
      * See {@link android.webkit.WebSettings#getDomStorageEnabled}.
      */
     public boolean getDomStorageEnabled() {
         synchronized (mAwSettingsLock) {
             return mDomStorageEnabled;
         }
     }
 
     @CalledByNative
     private boolean getDomStorageEnabledLocked() {
+        assert Thread.holdsLock(mAwSettingsLock);
         return mDomStorageEnabled;
     }
 
     /**
      * See {@link android.webkit.WebSettings#setDatabaseEnabled}.
      */
     public void setDatabaseEnabled(boolean flag) {
         synchronized (mAwSettingsLock) {
             if (mDatabaseEnabled != flag) {
                 mDatabaseEnabled = flag;
                 mEventHandler.updateWebkitPreferencesLocked();
             }
         }
     }
 
     /**
      * See {@link android.webkit.WebSettings#getDatabaseEnabled}.
      */
     public boolean getDatabaseEnabled() {
         synchronized (mAwSettingsLock) {
             return mDatabaseEnabled;
         }
     }
 
     @CalledByNative
     private boolean getDatabaseEnabledLocked() {
+        assert Thread.holdsLock(mAwSettingsLock);
         return mDatabaseEnabled;
     }
 
     /**
      * See {@link android.webkit.WebSettings#setDefaultTextEncodingName}.
      */
     public void setDefaultTextEncodingName(String encoding) {
         synchronized (mAwSettingsLock) {
             if (encoding != null && !mDefaultTextEncoding.equals(encoding)) {
                 mDefaultTextEncoding = encoding;
                 mEventHandler.updateWebkitPreferencesLocked();
             }
         }
     }
 
     /**
      * See {@link android.webkit.WebSettings#getDefaultTextEncodingName}.
      */
     public String getDefaultTextEncodingName() {
         synchronized (mAwSettingsLock) {
             return mDefaultTextEncoding;
         }
     }
 
     @CalledByNative
     private String getDefaultTextEncodingLocked() {
+        assert Thread.holdsLock(mAwSettingsLock);
         return mDefaultTextEncoding;
     }
 
     /**
      * See {@link android.webkit.WebSettings#setMediaPlaybackRequiresUserGesture}.
      */
     public void setMediaPlaybackRequiresUserGesture(boolean require) {
         synchronized (mAwSettingsLock) {
             if (mMediaPlaybackRequiresUserGesture != require) {
                 mMediaPlaybackRequiresUserGesture = require;
                 mEventHandler.updateWebkitPreferencesLocked();
             }
         }
     }
 
     /**
      * See {@link android.webkit.WebSettings#getMediaPlaybackRequiresUserGesture}.
      */
     public boolean getMediaPlaybackRequiresUserGesture() {
         synchronized (mAwSettingsLock) {
             return mMediaPlaybackRequiresUserGesture;
         }
     }
 
     @CalledByNative
     private boolean getMediaPlaybackRequiresUserGestureLocked() {
+        assert Thread.holdsLock(mAwSettingsLock);
         return mMediaPlaybackRequiresUserGesture;
     }
 
     /**
      * See {@link android.webkit.WebSettings#setDefaultVideoPosterURL}.
      */
     public void setDefaultVideoPosterURL(String url) {
         synchronized (mAwSettingsLock) {
             if (mDefaultVideoPosterURL != null && !mDefaultVideoPosterURL.equals(url) ||
                     mDefaultVideoPosterURL == null && url != null) {
                 mDefaultVideoPosterURL = url;
                 mEventHandler.updateWebkitPreferencesLocked();
             }
         }
     }
 
     /**
      * See {@link android.webkit.WebSettings#getDefaultVideoPosterURL}.
      */
     public String getDefaultVideoPosterURL() {
         synchronized (mAwSettingsLock) {
             return mDefaultVideoPosterURL;
         }
     }
 
     @CalledByNative
     private String getDefaultVideoPosterURLLocked() {
+        assert Thread.holdsLock(mAwSettingsLock);
         return mDefaultVideoPosterURL;
     }
 
     private void onGestureZoomSupportChanged(final boolean supportsGestureZoom) {
         // Always post asynchronously here, to avoid doubling back onto the caller.
         mEventHandler.maybePostOnUiThread(new Runnable() {
             @Override
             public void run() {
                 synchronized (mAwSettingsLock) {
                     if (mZoomChangeListener != null) {
@@ skipping 90 matching lines @@
         return size;
     }
 
     @CalledByNative
     private void updateEverything() {
         synchronized (mAwSettingsLock) {
             nativeUpdateEverythingLocked(mNativeAwSettings);
         }
     }
 
+    @CalledByNative
+    private void populateWebPreferences(long webPrefsPtr) {
+        synchronized (mAwSettingsLock) {
+            nativePopulateWebPreferencesLocked(mNativeAwSettings, webPrefsPtr);
+        }
+    }
+
     private void updateWebkitPreferencesOnUiThreadLocked() {
         if (mNativeAwSettings != 0) {
             assert mEventHandler.mHandler != null;
             ThreadUtils.assertOnUiThread();
             nativeUpdateWebkitPreferencesLocked(mNativeAwSettings);
         }
     }
 
     private native long nativeInit(long webContentsPtr);
 
     private native void nativeDestroy(long nativeAwSettings);
 
+    private native void nativePopulateWebPreferencesLocked(long nativeAwSettings, long webPrefsPtr);
+
     private native void nativeResetScrollAndScaleState(long nativeAwSettings);
 
     private native void nativeUpdateEverythingLocked(long nativeAwSettings);
 
     private native void nativeUpdateInitialPageScaleLocked(long nativeAwSettings);
 
     private native void nativeUpdateUserAgentLocked(long nativeAwSettings);
 
     private native void nativeUpdateWebkitPreferencesLocked(long nativeAwSettings);
 
     private static native String nativeGetDefaultUserAgent();
 
     private native void nativeUpdateFormDataPreferencesLocked(long nativeAwSettings);
 }