Update usage of Proguard in clank after moving Proguard to third_party.

chrome/android/java/proguard.flags

 # Keep line number information, useful for stack traces.
 -keepattributes SourceFile,LineNumberTable
 
 # Keep the annotations.
 -keep @interface ***
 
 # Disable obfuscation for the following two packages.
 -keepnames class com.google.android.apps.chrome.**,org.chromium.** {
   *;
 }
@@ skipping 13 matching lines @@
   @**.NativeCall <methods>;
   @**.UsedByReflection <methods>;
   @**.VisibleForTesting *;
   native <methods>;
 }
 
 # Keep all runtime visible annotations
 -keepattributes RuntimeVisibleAnnotations
 
 # Remove methods annotated with this if their return value is unused
--assumenosideeffects class * {
+-assumenosideeffects class com.google.android.apps.chrome.**,org.chromium.** {

[Yaron, 2015/08/25 16:57:35]

Ya, I think just revert this for now

   @org.chromium.base.annotations.RemovableInRelease <methods>;
 }
 
 # TODO(aurimas): figure out why we need to keep these classes.
 -keep class org.chromium.base.test.** {
   *;
 }
 
 # Keep protobuf code used via reflection
 # TODO(tonyg): Removing these -keeps results in new notes, but nothing seems to
@@ skipping 77 matching lines @@
 # that was deprecated in Android M. It is save to suppress this according to b/18510449.
 -dontwarn com.google.android.gms.common.GooglePlayServicesUtil
 
 # IntentUtils uses reflection to access a method that is hidden until API level 18.
 -dontnote org.chromium.chrome.browser.util.IntentUtils
 
 # Needed to compile ChromeTest.apk
 -keep class android.support.customtabs.ICustomTabsCallback** {
   *;
 }