Implement device-ram client hints header

content/child/blink_platform_impl.h

Index: content/child/blink_platform_impl.h
diff --git a/content/child/blink_platform_impl.h b/content/child/blink_platform_impl.h
index e43acb586ca47807976d02c82edc1767df07849b..7a558196b11ddae56f3a534182a850bcb3427737 100644
--- a/content/child/blink_platform_impl.h
+++ b/content/child/blink_platform_impl.h
@@ -74,6 +74,9 @@ class CONTENT_EXPORT BlinkPlatformImpl
   bool DatabaseSetFileSize(const blink::WebString& vfs_file_name,
                            long long size) override;
   size_t ActualMemoryUsageMB() override;
+  size_t AmountOfPhysicalMemoryMB() override;
+  // For testing.
+  void SetDevicePhysicalMemoryMBForTesting(int64_t physical_memory_mb) override;
   size_t NumberOfProcessors() override;
 
   size_t MaxDecodedImageBytes() override;
@@ -149,6 +152,7 @@ class CONTENT_EXPORT BlinkPlatformImpl
   scoped_refptr<NotificationDispatcher> notification_dispatcher_;
 
   blink::scheduler::WebThreadBase* compositor_thread_;
+  size_t physical_memory_mb_;
 };
 
 }  // namespace content