Implement device-ram client hints header

third_party/WebKit/Source/core/loader/FrameFetchContext.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 591 matching lines @@
   GetFrame()->Loader().ModifyRequestForCSP(resource_request, GetDocument());
 }
 
 void FrameFetchContext::AddClientHintsIfNecessary(
     const ClientHintsPreferences& hints_preferences,
     const FetchParameters::ResourceWidth& resource_width,
     ResourceRequest& request) {
   if (!RuntimeEnabledFeatures::clientHintsEnabled() || !GetDocument())
     return;
 
+  bool should_send_device_ram =

[panicker, 2017/05/05 17:19:30]

also check if device-ram RunTimeFlagEnabled  is enabled?

[fmeawad, 2017/05/23 20:50:54]

I don't think I need/should since ShouldSendDeviceRam already have that check.

+      GetDocument()->GetClientHintsPreferences().ShouldSendDeviceRam() ||
+      hints_preferences.ShouldSendDeviceRam();
   bool should_send_dpr =
       GetDocument()->GetClientHintsPreferences().ShouldSendDPR() ||
       hints_preferences.ShouldSendDPR();
   bool should_send_resource_width =
       GetDocument()->GetClientHintsPreferences().ShouldSendResourceWidth() ||
       hints_preferences.ShouldSendResourceWidth();
   bool should_send_viewport_width =
       GetDocument()->GetClientHintsPreferences().ShouldSendViewportWidth() ||
       hints_preferences.ShouldSendViewportWidth();
 
+  if (should_send_device_ram) {

[panicker, 2017/05/05 17:19:30]

Nit: extract this math into a helper
Also makes unittesting a bit easier

[fmeawad, 2017/05/23 20:50:54]

Done.

+    int physical_memory = Platform::Current()->AmountOfPhysicalMemoryMB();
+    int power = -1;
+    while (physical_memory != 0) {
+      physical_memory = physical_memory >> 1;
+      power++;
+    }
+    request.AddHTTPHeaderField(
+        "device-ram", AtomicString(String::Number((1 << power) / 1024.0)));
+  }
+
   if (should_send_dpr) {
     request.AddHTTPHeaderField(
         "DPR", AtomicString(String::Number(GetDocument()->DevicePixelRatio())));
   }
 
   if (should_send_resource_width) {
     if (resource_width.is_set) {
       float physical_width =
           resource_width.width * GetDocument()->DevicePixelRatio();
       request.AddHTTPHeaderField(
@@ skipping 143 matching lines @@
 std::unique_ptr<WebURLLoader> FrameFetchContext::CreateURLLoader() {
   return Platform::Current()->CreateURLLoader();
 }
 
 DEFINE_TRACE(FrameFetchContext) {
   visitor->Trace(document_loader_);
   BaseFetchContext::Trace(visitor);
 }
 
 }  // namespace blink