Add brotli content-encoding filter.

chrome/browser/io_thread.cc

Index: chrome/browser/io_thread.cc
diff --git a/chrome/browser/io_thread.cc b/chrome/browser/io_thread.cc
index 37b1c409ace3353e71124e5841b2d207b716397c..0b5519b81a0910b84b6a7771cb448e61772b65c9 100644
--- a/chrome/browser/io_thread.cc
+++ b/chrome/browser/io_thread.cc
@@ -825,6 +825,7 @@ void IOThread::Init() {
           switches::kEnableUserAlternateProtocolPorts)) {
     globals_->enable_user_alternate_protocol_ports = true;
   }
+  globals_->enable_brotli.set(ShouldEnableBrotli(command_line));
   // TODO(erikchen): Remove ScopedTracker below once http://crbug.com/466432
   // is fixed.
   tracked_objects::ScopedTracker tracking_profile13(
@@ -1097,6 +1098,8 @@ void IOThread::InitializeNetworkSessionParamsFromGlobals(
 
   globals.enable_npn.CopyToIfSet(&params->enable_npn);
 
+  globals.enable_brotli.CopyToIfSet(&params->enable_brotli);
+
   globals.enable_quic.CopyToIfSet(&params->enable_quic);
   globals.enable_quic_for_proxies.CopyToIfSet(&params->enable_quic_for_proxies);
   globals.quic_always_require_handshake_confirmation.CopyToIfSet(
@@ -1309,6 +1312,12 @@ void IOThread::ConfigureQuicGlobals(
   }
 }
 
+bool IOThread::ShouldEnableBrotli(const base::CommandLine& command_line) {
+  if (command_line.HasSwitch(switches::kDisableBrotli))
+    return false;
+  return command_line.HasSwitch(switches::kEnableBrotli);

[Randy Smith (Not in Mondays), 2015/12/04 16:07:52]

If I read this correctly, Brotli will be compiled in on non-iOS platforms,
disabled by default, and enabled only via flags or command lines.  Is your plan
to test with it manually for a bit before doing a finch experiment/default
enable?

[eustas, 2015/12/07 12:30:37]

I think we can actually have brotli enabled by default soon (there are not many
servers that can serve brotli encoded data).

I've chosen disabled-by-default to make this patch more clear (otherwise it
would require adding "br" to Accept-Encoding headers in integration tests).

+}
+
 bool IOThread::ShouldEnableQuic(const base::CommandLine& command_line,
                                 base::StringPiece quic_trial_group,
                                 bool quic_allowed_by_policy) {