Adds Lo-Fi fallback support for new Data Reduction Proxy protocol.

content/renderer/render_frame_impl.cc

Index: content/renderer/render_frame_impl.cc
diff --git a/content/renderer/render_frame_impl.cc b/content/renderer/render_frame_impl.cc
index 67ae44acdd11aee6bfad43f2c7fc953dcc39548b..7444b4313fb7fb560d0b01385e64b4f76c96aed4 100644
--- a/content/renderer/render_frame_impl.cc
+++ b/content/renderer/render_frame_impl.cc
@@ -132,6 +132,7 @@
 #include "content/renderer/pepper/pepper_audio_controller.h"
 #include "content/renderer/pepper/plugin_instance_throttler_impl.h"
 #include "content/renderer/presentation/presentation_dispatcher.h"
+#include "content/renderer/previews_state_helper.h"
 #include "content/renderer/push_messaging/push_messaging_client.h"
 #include "content/renderer/render_frame_proxy.h"
 #include "content/renderer/render_process.h"
@@ -3607,10 +3608,10 @@ void RenderFrameImpl::DidCommitProvisionalLoad(
   // main frame documents. Subframes inherit from the main frame and should not
   // change at commit time.
   if (is_main_frame_ && !navigation_state->WasWithinSameDocument()) {
-    previews_state_ =
-        extra_data ? extra_data->previews_state() : PREVIEWS_OFF;
-
+    previews_state_ = PREVIEWS_OFF;
     if (extra_data) {
+      previews_state_ = UpdatePreviewsStateFromMainFrameResponse(
+          extra_data->previews_state(), web_url_response);

[nasko, 2017/06/09 22:51:34]

Why not pass in only web_url_response? The extra_data comes from there as well
and can easily be made unconditional, where null extra_data returns
PREVIEWS_OFF.

[dougarnett, 2017/06/10 00:07:27]

I explored this a bit. I still need to determine extra_data here for the
effective_connection_type determination so it ends up looking like:

  if (is_main_frame_ && !navigation_state->WasWithinSameDocument()) {
    previews_state_ = GetPreviewsStateFromMainFrameResponse(web_url_response);
    WebURLResponseExtraDataImpl* extra_data =
        GetExtraDataFromResponse(web_url_response);
    if (extra_data) {
      effective_connection_type_ =
          EffectiveConnectionTypeToWebEffectiveConnectionType(
              extra_data->effective_connection_type());
    }
  }

Also, the GetExtraDataFromResponse() helper is local to this file so I am not
sure I want to extract extra_data in two places (and have both places know
WebURLResponseExtraDataImpl).

WDYT? Should I proceed with extracting extra_data in both places?



[An opposite way to go, would be to pull the header map out of the response (not
exposed currently though) and then pass the previews state and header map into
the helper.]

[nasko, 2017/06/12 17:38:50]

Thanks for looking into this. It is fine to stay as it is.

       effective_connection_type_ =
           EffectiveConnectionTypeToWebEffectiveConnectionType(
               extra_data->effective_connection_type());
@@ -4046,8 +4047,7 @@ bool RenderFrameImpl::ShouldUseClientLoFiForRequest(
 
   if (!(previews_state_ & CLIENT_LOFI_ON))
     return false;
-  if (previews_state_ &
-      (SERVER_LITE_PAGE_ON | PREVIEWS_OFF | PREVIEWS_NO_TRANSFORM)) {
+  if (previews_state_ & (PREVIEWS_OFF | PREVIEWS_NO_TRANSFORM)) {
     return false;
   }