The following revision refers to this bug:
  https://chrome-internal.googlesource.com/clank/internal/apps/+/ceb05c37ac01c226b9146ac4f1c51f80a35c09c9

commit ceb05c37ac01c226b9146ac4f1c51f80a35c09c9
Author: Sam Maier <smaier@google.com>
Date: Mon Jul 11 18:48:27 2016

I've looked into changing the -keepnames class *** { *; } line from WebView's proguard.flags.

Keeping the line as-is (with https://codereview.chromium.org/2147743002/) for system_webview_google_apk gives us:

1086108 .dex size
10066 methods
1847 types
3442 fields
11027 strings
105528 bytes of permanent dirty memory

Changing the line to -keepnames,allowoptimization class *** { *; } gives us:
1034148 .dex size
9414 methods
1764 types
3265 fields
10449 strings
99568 bytes of permanent dirty memory

Removing the line altogether (and thus, allowing obfuscation to take place) gives us:
938556 .dex size
9414 methods
1764 types
3265 fields
7303 strings
86984 bytes of permanent dirty memory

As for the stacktraces that come out of these changes, I think a WebView team member would be better suited to judge them. 

Thanks for the data. Once you've landed the current CLs, I can try to take a look at this?

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/6eff9fcd9bce74c436c3ce33355f1b7acbcc3b34

commit 6eff9fcd9bce74c436c3ce33355f1b7acbcc3b34
Author: smaier <smaier@chromium.org>
Date: Thu Jul 14 14:36:22 2016

Fixing WebView ProGuard config for annotations

WebView used to not -keep its annotations. Thus, when trying to do
anything useful with ProGuard, it appeared that the annotations were not
being obeyed, since ProGuard had already stripped them out.

Note - since we still have the -keepnames class *** { *; }, this effectively
prevents any real optimizations from being run.

This change brings the .dex size down 7356 B, and removes 12 types, 5 fields,
and 57 strings. However, these all seem inconsequential, as this is the
method/class diff of this change:

org.chromium.base.Log
-  void d(java.lang.String,java.lang.String,java.lang.Object)
-  void v(java.lang.String,java.lang.String)
-  void d(java.lang.String,java.lang.String,java.lang.Object,java.lang.Object,java.lang.Object)
-  java.lang.String formatLogWithStack(java.lang.String,java.lang.Object[])
-  void d(java.lang.String,java.lang.String)
-  void v(java.lang.String,java.lang.String,java.lang.Object,java.lang.Object,java.lang.Object)
-  void <init>()
-  void d(java.lang.String,java.lang.String,java.lang.Object,java.lang.Object)
-  java.lang.String getCallOrigin()
-  void debug(java.lang.String,java.lang.String,java.lang.Object[])
-  void verbose(java.lang.String,java.lang.String,java.lang.Object[])

BUG= 541543 ,583143,624827, 627139 

Review-Url: https://codereview.chromium.org/2147743002
Cr-Commit-Position: refs/heads/master@{#405491}

[modify] https://crrev.com/6eff9fcd9bce74c436c3ce33355f1b7acbcc3b34/android_webview/apk/java/proguard.flags

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/0e0838f9baa10ec6382faf06ba37b6e1a6f80d6c

commit 0e0838f9baa10ec6382faf06ba37b6e1a6f80d6c
Author: smaier <smaier@chromium.org>
Date: Tue Aug 16 20:35:59 2016

Turning optimizations on for the bulk of webview

This shaves 85kb from the .dex size and 10kb from memory overhead.

BUG= 627139 

Review-Url: https://codereview.chromium.org/2240483002
Cr-Commit-Position: refs/heads/master@{#412329}

[modify] https://crrev.com/0e0838f9baa10ec6382faf06ba37b6e1a6f80d6c/android_webview/apk/java/proguard.flags

Yesterday's commit officially turns this on.