Create a star symbol for gaps at the start & end of sections

tools/binary_size/libsupersize/testdata/Archive_Elf.golden

Index: tools/binary_size/libsupersize/testdata/Archive_Elf.golden
diff --git a/tools/binary_size/libsupersize/testdata/Archive_Elf.golden b/tools/binary_size/libsupersize/testdata/Archive_Elf.golden
index 542e8e168772ef07e1ddbf4083f93ccd986d16f0..e5e35ce65f727cd11858d426b54f4f313179181c 100644
--- a/tools/binary_size/libsupersize/testdata/Archive_Elf.golden
+++ b/tools/binary_size/libsupersize/testdata/Archive_Elf.golden
@@ -5,26 +5,22 @@ elf_mtime={redacted}
 git_revision=abc123
 gn_args=var1=true var2="foo"
 map_file_name=../test.map
-Section r: has 44.6% of 2641540 bytes accounted for from 7 symbols. 3286112 bytes are unaccounted for.
-* Padding accounts for 366 bytes (0.0%)
-* Contains 0 aliases
+Section r: has 100.0% of 5927652 bytes accounted for from 9 symbols. 0 bytes are unaccounted for.
+* Padding accounts for 11 bytes (0.0%)
+* 4 placeholders (symbols that start with **) account for 5927509.0 bytes (100.0%)
 * 0 symbols have shared ownership
-* Without 2 merge sections (accounting for 2641394 bytes):
-  * Section r: has 0.0% of 146 bytes accounted for from 5 symbols. 5927506 bytes are unaccounted for.
 Section b: has 40.3% of 524520 bytes accounted for from 6 symbols. 775936 bytes are unaccounted for.
 * Padding accounts for 196 bytes (0.0%)
-* Contains 0 aliases
 * 0 symbols have shared ownership
-Section d: has 40.4% of 790284 bytes accounted for from 13 symbols. 1166732 bytes are unaccounted for.
+Section d: has 100.0% of 1957016 bytes accounted for from 15 symbols. 0 bytes are unaccounted for.
 * Padding accounts for 16 bytes (0.0%)
-* Contains 0 aliases
+* 2 placeholders (symbols that start with **) account for 1166732.0 bytes (59.6%)
 * 0 symbols have shared ownership
-Section t: has 0.2% of 79710 bytes accounted for from 17 symbols. 35821002 bytes are unaccounted for.
-* Padding accounts for 9806 bytes (12.3%)
-* Contains 5 aliases, mapped to 2 addresses (60 bytes)
+Section t: has 100.0% of 35900712 bytes accounted for from 18 symbols. 0 bytes are unaccounted for.
+* Padding accounts for 48 bytes (0.0%)
+* 3 placeholders (symbols that start with **) account for 35830760.0 bytes (99.8%)
+* Contains 5 aliases, mapped to 2 unique addresses (60 bytes)
 * 1 symbols have shared ownership (12 bytes)
-* Without 2 merge sections (accounting for 9758 bytes):
-  * Section t: has 0.2% of 69952 bytes accounted for from 15 symbols. 35830760 bytes are unaccounted for.
 .bss@0(size_without_padding=262144,padding=0,name=ff_cos_131072,object_path=third_party/ffmpeg/libffmpeg_internal.a/fft_float.o,source_path=third_party/fft_float.cc,flags={})
 .bss@0(size_without_padding=131072,padding=0,name=ff_cos_131072_fixed,object_path=third_party/ffmpeg/libffmpeg_internal.a/fft_fixed.o,source_path=third_party/fft_fixed.cc,flags={})
 .bss@0(size_without_padding=131072,padding=0,name=ff_cos_65536,object_path=third_party/ffmpeg/libffmpeg_internal.a/fft_float.o,source_path=third_party/fft_float.cc,flags={})
@@ -36,21 +32,25 @@ Section t: has 0.2% of 79710 bytes accounted for from 17 symbols. 35821002 bytes
 .data@2de7008(size_without_padding=152,padding=0,name=base::android::kBaseRegisteredMethods,object_path=third_party/WebKit.a/ContiguousContainer.o,source_path=third_party/container.c,flags={rel})
 .data@2de70a0(size_without_padding=4,padding=0,name=base::android::g_renderer_histogram_code,object_path=third_party/WebKit.a/ContiguousContainer.o,source_path=third_party/container.c,flags={anon})
 .data@2de70a4(size_without_padding=4,padding=0,name=base::android::g_library_version_number,object_path=third_party/WebKit.a/ContiguousContainer.o,source_path=third_party/container.c,flags={anon,rel.loc})
+.data@2dffd88(size_without_padding=0,padding=101600,name=** symbol gap 3 (end of section),object_path=,source_path=,flags={})
 .data.rel.ro@2cd8500(size_without_padding=56,padding=0,name=ChromeMainDelegateAndroid [vtable],object_path=third_party/WebKit.a/PaintChunker.o,source_path=third_party/paint.cc,flags={})
 .data.rel.ro@2cd8538(size_without_padding=24,padding=0,name=mojo::MessageReceiver [vtable],object_path=base/base/page_allocator.o,source_path=base/page_allocator.cc,flags={})
 .data.rel.ro@2cd8550(size_without_padding=12,padding=0,name=kMethodsAnimationFrameTimeHistogram,object_path=base/base/page_allocator.o,source_path=base/page_allocator.cc,flags={})
+.data.rel.ro@2ddc608(size_without_padding=0,padding=1065132,name=** symbol gap 3 (end of section),object_path=,source_path=,flags={})
 .data.rel.ro.local@2c176f0(size_without_padding=56,padding=0,name=ChromeMainDelegate [vtable],object_path=third_party/icu/icuuc/ucnv_ext.o,source_path=third_party/icu/ucnv_ext.c,flags={})
 .data.rel.ro.local@2c17728(size_without_padding=24,padding=0,name=chrome::mojom::FieldTrialRecorder [vtable],object_path=third_party/icu/icuuc/ucnv_ext.o,source_path=third_party/icu/ucnv_ext.c,flags={})
 .data.rel.ro.local@2c17740(size_without_padding=789904,padding=0,name=chrome::mojom::FieldTrialRecorderProxy [vtable],object_path=third_party/WebKit.a/ContiguousContainer.o,source_path=third_party/container.c,flags={})
 .data.rel.ro.local@2cd84e0(size_without_padding=16,padding=16,name=.Lswitch.table.45,object_path=third_party/gvr-android-sdk/libgvr_shim_static_arm.a/libcontroller_api_impl.a_controller_api_impl.o,source_path=,flags={})
 .data.rel.ro.local@2cd84f0(size_without_padding=8,padding=0,name=kSystemClassPrefixes,object_path=third_party/gvr-android-sdk/libgvr_shim_static_arm.a/libport_android_jni.a_jni_utils.o,source_path=,flags={anon})
 .rodata@266e600(size_without_padding=1965409,padding=0,name=** merge strings,object_path=,source_path=,flags={})
-.rodata@284e364(size_without_padding=8,padding=3,name=,object_path=base/base/page_allocator.o,source_path=base/page_allocator.cc,flags={})
+.rodata@284e364(size_without_padding=0,padding=3,name=** symbol gap 2,object_path=base/base/page_allocator.o,source_path=base/page_allocator.cc,flags={})
+.rodata@284e364(size_without_padding=8,padding=0,name=,object_path=base/base/page_allocator.o,source_path=base/page_allocator.cc,flags={})
 .rodata@284e370(size_without_padding=40,padding=4,name=Name,object_path=base/base/page_allocator.o,source_path=base/page_allocator.cc,flags={})
 .rodata@284e398(size_without_padding=32,padding=0,name=chrome::mojom::FilePatcher::Name_,object_path=third_party/WebKit.a/ContiguousContainer.o,source_path=third_party/container.c,flags={})
 .rodata@284e518(size_without_padding=675633,padding=352,name=** merge strings,object_path=,source_path=,flags={})
 .rodata@28f3450(size_without_padding=48,padding=7,name=kAnimationFrameTimeHistogramClassPath,object_path=third_party/WebKit.a/PaintChunker.o,source_path=third_party/paint.cc,flags={anon})
 .rodata@28f3480(size_without_padding=4,padding=0,name=blink::CSSValueKeywordsHash::findValueImpl::value_word_list,object_path=third_party/WebKit.a/PaintChunker.o,source_path=third_party/paint.cc,flags={anon})
+.rodata@2c158e4(size_without_padding=0,padding=3286112,name=** symbol gap 3 (end of section),object_path=,source_path=,flags={})
 .text@28d900(size_without_padding=16,padding=0,name=_GLOBAL__sub_I_page_allocator.cc,object_path=base/base/page_allocator.o,source_path=base/page_allocator.cc,flags={startup})
 .text@28d910(size_without_padding=56,padding=0,name=_GLOBAL__sub_I_bbr_sender.cc,object_path=base/base/page_allocator.o,source_path=base/page_allocator.cc,flags={startup})
 .text@28d948(size_without_padding=28,padding=0,name=_GLOBAL__sub_I_pacing_sender.cc,object_path=base/base/page_allocator.o,source_path=base/page_allocator.cc,flags={startup})
@@ -68,3 +68,4 @@ Section t: has 0.2% of 79710 bytes accounted for from 17 symbols. 35821002 bytes
 .text@2a0020(size_without_padding=24,padding=4,name=blink::ContiguousContainerBase::ContiguousContainerBase,object_path=third_party/WebKit.a/ContiguousContainer.o,source_path=third_party/container.c,flags={})
 .text@2a1000(size_without_padding=0,padding=4040,name=** symbol gap 1,object_path=third_party/WebKit.a/ContiguousContainer.o,source_path=third_party/container.c,flags={})
 .text@2a1000(size_without_padding=94,padding=0,name=blink::PaintChunker::releasePaintChunks [clone .part.1],object_path=third_party/WebKit.a/ContiguousContainer.o,source_path=third_party/container.c,flags={anon})
+.text@24ca628(size_without_padding=0,padding=35821002,name=** symbol gap 2 (end of section),object_path=,source_path=,flags={})