Implement device-ram client hints header

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

Index: third_party/WebKit/Source/core/loader/FrameFetchContext.cpp
diff --git a/third_party/WebKit/Source/core/loader/FrameFetchContext.cpp b/third_party/WebKit/Source/core/loader/FrameFetchContext.cpp
index 66037130cf252856d97c8c24965652c8d0f53139..63f14241d0ef3256e4a7acb618e6638a73a0532d 100644
--- a/third_party/WebKit/Source/core/loader/FrameFetchContext.cpp
+++ b/third_party/WebKit/Source/core/loader/FrameFetchContext.cpp
@@ -609,6 +609,9 @@ void FrameFetchContext::AddClientHintsIfNecessary(
   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();
@@ -619,6 +622,17 @@ void FrameFetchContext::AddClientHintsIfNecessary(
       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())));