Version: Tip of master as of today ( 637c0b137e0e14df23c34260277ce90617711ac1 )
OS: Linux (Any)

What steps will reproduce the problem?
(1) Set up a Linux workspace with this GN file: https://cs.chromium.org/chromium/src/build/args/headless.gn?q=build/args/headless.gn&sq=package:chromium&l=1
(Note: I also set "is_debug = false" and "target_os = linux", though I doubt that had any impact
(2) "ninja -C out/GN-Headless"
(Or for faster failure: "ninja -C out/GN-Headless media_transfer_protocol"
(3)

What is the expected output?
Build succeeds

What do you see instead?
[1/3] CXX obj/device/media_transfer_protocol/media_transfer_protocol/media_transfer_protocol_daemon_client.o
FAILED: obj/device/media_transfer_protocol/media_transfer_protocol/media_transfer_protocol_daemon_client.o 
../../third_party/llvm-build/Release+Asserts/bin/clang++ -MMD -MF obj/device/media_transfer_protocol/media_transfer_protocol/media_transfer_protocol_daemon_client.o.d -DV8_DEPRECATION_WARNINGS -DENABLE_MDNS=1 -DENABLE_NOTIFICATIONS -DENABLE_PEPPER_CDMS -DENABLE_PLUGINS=1 -DENABLE_PDF=1 -DENABLE_SPELLCHECK=1 -DUI_COMPOSITOR_IMAGE_TRANSPORT -DUSE_AURA=1 -DUSE_DEFAULT_RENDER_THEME=1 -DUSE_NSS_CERTS=1 -DUSE_OZONE=1 -DENABLE_WEBRTC=1 -DDISABLE_NACL -DENABLE_EXTENSIONS=1 -DENABLE_TASK_MANAGER=1 -DENABLE_THEMES=1 -DENABLE_CAPTIVE_PORTAL_DETECTION=1 -DENABLE_SESSION_SERVICE=1 -DENABLE_SUPERVISED_USERS=1 -DENABLE_SERVICE_DISCOVERY=1 -DFULL_SAFE_BROWSING -DSAFE_BROWSING_CSD -DSAFE_BROWSING_DB_LOCAL -DCHROMIUM_BUILD -DENABLE_MEDIA_ROUTER=1 -DFIELDTRIAL_TESTING_ENABLED -DSLATIUM_EXPORT=__attribute__\(\(visibility\(\"default\"\)\)\) -DCOMPONENT_BUILD=1 -DHAVE_VISIBILITY_ATTRIBUTE -DV8_SHARED -DBUILDING_V8_SHARED -DCR_CLANG_REVISION=274369-1 -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -DNDEBUG -DNVALGRIND -DDYNAMIC_ANNOTATIONS_ENABLED=0 -DGOOGLE_PROTOBUF_NO_RTTI -DGOOGLE_PROTOBUF_NO_STATIC_INITIALIZER -DHAVE_PTHREAD -I../.. -Igen -I../../third_party/protobuf/src -Igen/protoc_out -I../../third_party/protobuf/src -fno-strict-aliasing --param=ssp-buffer-size=4 -fstack-protector -funwind-tables -fPIC -pipe -B../../third_party/binutils/Linux_x64/Release/bin -fcolor-diagnostics -fdebug-prefix-map=/media/SecondHDD/workspaces/linux/src=. -pthread -m64 -march=x86-64 -Wall -Werror -Wextra -Wno-missing-field-initializers -Wno-unused-parameter -Wno-c++11-narrowing -Wno-covered-switch-default -Wno-deprecated-register -Wno-unneeded-internal-declaration -Wno-inconsistent-missing-override -Wno-shift-negative-value -Wno-undefined-var-template -O2 -fno-ident -fdata-sections -ffunction-sections -g0 --sysroot=../../build/linux/debian_wheezy_amd64-sysroot -fvisibility=hidden -Xclang -load -Xclang ../../third_party/llvm-build/Release+Asserts/lib/libFindBadConstructs.so -Xclang -add-plugin -Xclang find-bad-constructs -Xclang -plugin-arg-find-bad-constructs -Xclang check-templates -Xclang -plugin-arg-find-bad-constructs -Xclang follow-macro-expansion -Xclang -plugin-arg-find-bad-constructs -Xclang check-implicit-copy-ctors -Xclang -plugin-arg-find-bad-constructs -Xclang check-ipc -Wheader-hygiene -Wstring-conversion -fno-threadsafe-statics -fvisibility-inlines-hidden -std=gnu++11 -fno-rtti -fno-exceptions -c ../../device/media_transfer_protocol/media_transfer_protocol_daemon_client.cc -o obj/device/media_transfer_protocol/media_transfer_protocol/media_transfer_protocol_daemon_client.o
In file included from ../../device/media_transfer_protocol/media_transfer_protocol_daemon_client.cc:12:
../../dbus/bus.h:8:10: fatal error: 'dbus/dbus.h' file not found
#include <dbus/dbus.h>
         ^
1 error generated.
[2/3] CXX obj/device/media_transfer_protocol/media_transfer_protocol/media_transfer_protocol_manager.o
FAILED: obj/device/media_transfer_protocol/media_transfer_protocol/media_transfer_protocol_manager.o 
../../third_party/llvm-build/Release+Asserts/bin/clang++ -MMD -MF obj/device/media_transfer_protocol/media_transfer_protocol/media_transfer_protocol_manager.o.d -DV8_DEPRECATION_WARNINGS -DENABLE_MDNS=1 -DENABLE_NOTIFICATIONS -DENABLE_PEPPER_CDMS -DENABLE_PLUGINS=1 -DENABLE_PDF=1 -DENABLE_SPELLCHECK=1 -DUI_COMPOSITOR_IMAGE_TRANSPORT -DUSE_AURA=1 -DUSE_DEFAULT_RENDER_THEME=1 -DUSE_NSS_CERTS=1 -DUSE_OZONE=1 -DENABLE_WEBRTC=1 -DDISABLE_NACL -DENABLE_EXTENSIONS=1 -DENABLE_TASK_MANAGER=1 -DENABLE_THEMES=1 -DENABLE_CAPTIVE_PORTAL_DETECTION=1 -DENABLE_SESSION_SERVICE=1 -DENABLE_SUPERVISED_USERS=1 -DENABLE_SERVICE_DISCOVERY=1 -DFULL_SAFE_BROWSING -DSAFE_BROWSING_CSD -DSAFE_BROWSING_DB_LOCAL -DCHROMIUM_BUILD -DENABLE_MEDIA_ROUTER=1 -DFIELDTRIAL_TESTING_ENABLED -DSLATIUM_EXPORT=__attribute__\(\(visibility\(\"default\"\)\)\) -DCOMPONENT_BUILD=1 -DHAVE_VISIBILITY_ATTRIBUTE -DV8_SHARED -DBUILDING_V8_SHARED -DCR_CLANG_REVISION=274369-1 -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -DNDEBUG -DNVALGRIND -DDYNAMIC_ANNOTATIONS_ENABLED=0 -DGOOGLE_PROTOBUF_NO_RTTI -DGOOGLE_PROTOBUF_NO_STATIC_INITIALIZER -DHAVE_PTHREAD -I../.. -Igen -I../../third_party/protobuf/src -Igen/protoc_out -I../../third_party/protobuf/src -fno-strict-aliasing --param=ssp-buffer-size=4 -fstack-protector -funwind-tables -fPIC -pipe -B../../third_party/binutils/Linux_x64/Release/bin -fcolor-diagnostics -fdebug-prefix-map=/media/SecondHDD/workspaces/linux/src=. -pthread -m64 -march=x86-64 -Wall -Werror -Wextra -Wno-missing-field-initializers -Wno-unused-parameter -Wno-c++11-narrowing -Wno-covered-switch-default -Wno-deprecated-register -Wno-unneeded-internal-declaration -Wno-inconsistent-missing-override -Wno-shift-negative-value -Wno-undefined-var-template -O2 -fno-ident -fdata-sections -ffunction-sections -g0 --sysroot=../../build/linux/debian_wheezy_amd64-sysroot -fvisibility=hidden -Xclang -load -Xclang ../../third_party/llvm-build/Release+Asserts/lib/libFindBadConstructs.so -Xclang -add-plugin -Xclang find-bad-constructs -Xclang -plugin-arg-find-bad-constructs -Xclang check-templates -Xclang -plugin-arg-find-bad-constructs -Xclang follow-macro-expansion -Xclang -plugin-arg-find-bad-constructs -Xclang check-implicit-copy-ctors -Xclang -plugin-arg-find-bad-constructs -Xclang check-ipc -Wheader-hygiene -Wstring-conversion -fno-threadsafe-statics -fvisibility-inlines-hidden -std=gnu++11 -fno-rtti -fno-exceptions -c ../../device/media_transfer_protocol/media_transfer_protocol_manager.cc -o obj/device/media_transfer_protocol/media_transfer_protocol/media_transfer_protocol_manager.o
In file included from ../../device/media_transfer_protocol/media_transfer_protocol_manager.cc:24:
../../dbus/bus.h:8:10: fatal error: 'dbus/dbus.h' file not found
#include <dbus/dbus.h>
         ^
1 error generated.
ninja: build stopped: subcommand failed.


Please use labels and text to provide additional information.
Note: I tested this on today's tip of master, as well as on an early August workspace. Both fail with the same error. There might be other targets failing further down the line as well.