Remove data reduction proxy code.

android_webview/apk/java/proguard.flags

 # Don't rename anything, it makes stack traces unintelligible. We only allow the
 # obfuscation pass to run so that we can discard attributes like local variable
 # tables.
 -keepnames class *** { *; }
 
 # Keep source file and line number information for stack traces.
 -keepattributes SourceFile,LineNumberTable
 
 # Keep all runtime visible annotations.
 -keepattributes RuntimeVisibleAnnotations
@@ skipping 52 matching lines @@
 -dontnote org.chromium.net.ProxyChangeListener$ProxyReceiver
 
 # Silence warnings about reflection used to check for onShow/HideCustomView.
 # This class is not really kept since it's in a library jar.
 -keep class android.webkit.WebChromeClient {
   void onShowCustomView(...);
   void onHideCustomView();
 }
 
 # Accessed via reflection but not present in all builds
--keep class com.android.webview.chromium.Drp {
-  public java.lang.String KEY;
-}
--dontnote com.android.webview.chromium.Drp
 -keep class com.android.webview.chromium.PlatformServiceBridgeGoogle {
   void setMetricsSettingListener(...);
   PlatformServiceBridgeGoogle(...);
 }
 -dontnote com.android.webview.chromium.PlatformServiceBridgeGoogle
 
 # AwDebug is accessed by reflection.
 -keep class org.chromium.android_webview.AwDebug {
   public static boolean dumpWithoutCrashing(...);
 }
 
 #TODO(hush): remove after N release. crbug.com/546762
 -keep class com.android.webview.chromium.ContentSettingsAdapter {
   public void setDisabledActionModeMenuItems(int);
   public int getDisabledActionModeMenuItems();
 }
 
 # Ignore notes and warnings about the support library, which uses reflection and
 # may reference classes no longer in the SDK.
 -dontnote android.support.**
 -dontwarn android.support.**
 
 # Keep all enum values and valueOf methods. See
 # http://proguard.sourceforge.net/index.html#manual/examples.html
 # for the reason for this. Also, see http://crbug.com/248037.
 -keepclassmembers enum * {
     public static **[] values();
     public static ** valueOf(java.lang.String);
 }