Revert of Fix (or tag) uses of explicit '64' instead of GL_MAILBOX_SIZE_CHROMIUM (https://codereview.chromium.org/138763009/)

Reason for revert:
FAILED: c++ -MMD -MF obj/cc/layers/cc_unittests.texture_layer_unittest.o.d -DV8_DEPRECATION_WARNINGS -D_FILE_OFFSET_BITS=64 -DCHROMIUM_BUILD -DCOMPONENT_BUILD -DTOOLKIT_VIEWS=1 -DUI_COMPOSITOR_IMAGE_TRANSPORT -DUSE_AURA=1 -DUSE_ASH=1 -DUSE_CAIRO=1 -DUSE_GLIB=1 -DUSE_DEFAULT_RENDER_THEME=1 -DUSE_NSS=1 -DUSE_X11=1 -DOS_CHROMEOS=1 -DUSE_XI2_MT=2 -DIMAGE_LOADER_EXTENSION=1 -DENABLE_REMOTING=1 -DENABLE_WEBRTC=1 -DUSE_PROPRIETARY_CODECS -DENABLE_PEPPER_CDMS -DENABLE_CONFIGURATION_POLICY -DENABLE_INPUT_SPEECH -DENABLE_NOTIFICATIONS -DENABLE_HIDPI=1 -DUSE_UDEV -DENABLE_EGLIMAGE=1 -DENABLE_TASK_MANAGER=1 -DENABLE_EXTENSIONS=1 -DENABLE_PLUGINS=1 -DENABLE_SESSION_SERVICE=1 -DENABLE_THEMES=1 -DENABLE_AUTOFILL_DIALOG=1 -DENABLE_BACKGROUND=1 -DENABLE_AUTOMATION=1 -DENABLE_GOOGLE_NOW=1 -DCLD_VERSION=2 -DENABLE_FULL_PRINTING=1 -DENABLE_PRINTING=1 -DENABLE_SPELLCHECK=1 -DENABLE_CAPTIVE_PORTAL_DETECTION=1 -DENABLE_APP_LIST=1 -DENABLE_MANAGED_USERS=1 -DENABLE_MDNS=1 -DGTEST_HAS_POSIX_RE=0 -DGL_GLEXT_PROTOTYPES -DSKIA_DLL -DGR_GL_IGNORE_ES3_MSAA=0 -DSK_ENABLE_INST_COUNT=0 -DSK_SUPPORT_GPU=1 '-DGR_GL_CUSTOM_SETUP_HEADER="GrGLConfig_chrome.h"' -DSK_ENABLE_LEGACY_API_ALIASING=1 -DSK_ATTR_DEPRECATED=SK_NOTHING_ARG1 -DSK_USE_POSIX_THREADS -DSK_DEFERRED_CANVAS_USES_FACTORIES=1 -DUNIT_TEST -DGTEST_HAS_RTTI=0 -DU_USING_ICU_NAMESPACE=0 -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -DNDEBUG -DNVALGRIND -DDYNAMIC_ANNOTATIONS_ENABLED=0 -D_FORTIFY_SOURCE=2 -I../../cc/test -I../../cc -I../.. -I../../third_party/khronos -I../../gpu -I../../skia/config -I../../third_party/skia/src/core -I../../third_party/skia/include/core -I../../third_party/skia/include/effects -I../../third_party/skia/include/pdf -I../../third_party/skia/include/gpu -I../../third_party/skia/include/lazy -I../../third_party/skia/include/pathops -I../../third_party/skia/include/pipe -I../../third_party/skia/include/ports -I../../third_party/skia/include/utils -I../../skia/ext -I../../testing/gmock/include -I../../testing/gtest/include -I../../third_party/icu/source/i18n -I../../third_party/icu/source/common -Werror -pthread -fno-exceptions -fno-strict-aliasing -Wall -Wno-unused-parameter -Wno-missing-field-initializers -fvisibility=hidden -pipe -fPIC -pthread -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -O2 -fno-ident -fdata-sections -ffunction-sections -funwind-tables -fno-rtti -fno-threadsafe-statics -fvisibility-inlines-hidden -Wsign-compare  -c ../../cc/layers/texture_layer_unittest.cc -o obj/cc/layers/cc_unittests.texture_layer_unittest.o
In file included from ../../testing/gmock/include/gmock/gmock-spec-builders.h:71:0,
                 from ../../testing/gmock/include/gmock/gmock-generated-function-mockers.h:43,
                 from ../../testing/gmock/include/gmock/gmock.h:61,
                 from ../../cc/layers/texture_layer_unittest.cc:33:
../../testing/gmock/include/gmock/gmock-matchers.h: In member function 'bool testing::internal::EqMatcher<Rhs>::Impl<Lhs>::MatchAndExplain(Lhs, testing::MatchResultListener*) const [with Lhs = const gpu::Mailbox&, Rhs = gpu::Mailbox]':
../../cc/layers/texture_layer_unittest.cc:2173:1:   instantiated from here
../../testing/gmock/include/gmock/gmock-matchers.h:784:1: error: no match for 'operator==' in 'lhs == ((const testing::internal::EqMatcher<gpu::Mailbox>::Impl<const gpu::Mailbox&>*)this)->testing::internal::EqMatcher<gpu::Mailbox>::Impl<const gpu::Mailbox&>::rhs_'
../../testing/gmock/include/gmock/gmock-matchers.h:784:1: note: candidate is:
../../testing/gtest/include/gtest/internal/gtest-linked_ptr.h:213:6: note: template<class T> bool testing::internal::operator==(T*, const testing::internal::linked_ptr<T>&)
../../testing/gmock/include/gmock/gmock-matchers.h:784:1: error: control reaches end of non-void function [-Werror=return-type]


Original issue's description:
> Fix (or tag) uses of explicit '64' instead of GL_MAILBOX_SIZE_CHROMIUM
> 
> That way we can easily change the size later. Security says 64 may be overkill.
> 
> BUG=None
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=251306

TBR=danakj@chromium.org,piman@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=None

Review URL: https://codereview.chromium.org/166853002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251309 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 251309