ui: Rename gfx::BufferUsage enum values and add BufferUsage::GPU_READ.

The problem with the current usage modes is that we currently use
SCANOUT for anything that doesn't require CPU access. When importing
a buffer we typically don't care about anything but having the GPU
be able to read from it. SCANOUT is not a good description of that
and currently means GPU read/write support.

This patch attempts to make usage more explicit and it solves the
use case where a buffer type can only provide GPU read and not GPU
write support (e.g. SHM fallback). Here are the new usage modes:

- GPU_READ
- GPU_READ_WRITE
- GPU_READ_CPU_READ_WRITE

GPU_READ is useful when importing a buffer and all you care about is
being able to use it for sampling and optionally scanout.

GPU_READ_WRITE is useful for things like WebGL or GPU raster where
we want the ability to write to the buffer using GL and potentially
use it for scanout.

GPU_READ_CPU_READ_WRITE is the usage mode that allows CPU access and
is used for one-copy and zero-copy texture initialization. There's
nothing preventing this mode from also supporting scanout.

- GPU_READ_CPU_READ_WRITE_PERSISTENT

This usage mode indicates that the data will be persistent across
Unmap()/Map() calls but will likely become part of the normal
GPU_READ_CPU_READ_WRITE usage once all buffer types support this.

BUG=538325
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/1420923005

Cr-Commit-Position: refs/heads/master@{#356108}

11 files changed, 16 insertions, 49 deletions

diff --git a/gpu/GLES2/extensions/CHROMIUM/CHROMIUM_gpu_memory_buffer_image.txt b/gpu/GLES2/extensions/CHROMIUM/CHROMIUM_gpu_memory_buffer_image.txt
index 9f4d09d..d185894 100644
--- a/gpu/GLES2/extensions/CHROMIUM/CHROMIUM_gpu_memory_buffer_image.txt
+++ b/gpu/GLES2/extensions/CHROMIUM/CHROMIUM_gpu_memory_buffer_image.txt
@@ -29,8 +29,7 @@ New Tokens
 
     Accepted by the <usage> parameter of CreateGpuMemoryBufferImageCHROMIUM:
 
-        MAP_CHROMIUM 0x78F1
-        SCANOUT_CHROMIUM 0x78F2
+        READ_WRITE_CHROMIUM 0x78F2
 
 New Procedures and Functions
 
@@ -50,8 +49,7 @@ New Procedures and Functions
     INVALID_ENUM is generated if <internalformat> is not one of
     RGB or RGBA.
 
-    INVALID_ENUM is generated if <usage> is not one of
-    MAP_CHROMIUM or SCANOUT_CHROMIUM.
+    INVALID_ENUM is generated if <usage> is not READ_WRTIE_CHROMIUM.
 
 Errors
 
diff --git a/gpu/GLES2/gl2extchromium.h b/gpu/GLES2/gl2extchromium.h
index a79b3e7..31958b3 100644
--- a/gpu/GLES2/gl2extchromium.h
+++ b/gpu/GLES2/gl2extchromium.h
@@ -111,12 +111,8 @@ typedef void (
 #ifndef GL_CHROMIUM_gpu_memory_buffer_image
 #define GL_CHROMIUM_gpu_memory_buffer_image 1
 
-#ifndef GL_MAP_CHROMIUM
-#define GL_MAP_CHROMIUM 0x78F1
-#endif
-
-#ifndef GL_SCANOUT_CHROMIUM
-#define GL_SCANOUT_CHROMIUM 0x78F2
+#ifndef GL_READ_WRITE_CHROMIUM
+#define GL_READ_WRITE_CHROMIUM 0x78F2
 #endif
 
 #ifndef GL_RGB_YUV_420_CHROMIUM
diff --git a/gpu/command_buffer/build_gles2_cmd_buffer.py b/gpu/command_buffer/build_gles2_cmd_buffer.py
index 6c1a705..a1071ab 100755
--- a/gpu/command_buffer/build_gles2_cmd_buffer.py
+++ b/gpu/command_buffer/build_gles2_cmd_buffer.py
@@ -1861,8 +1861,7 @@ _NAMED_TYPE_INFO = {
   'ImageUsage': {
     'type': 'GLenum',
     'valid': [
-      'GL_MAP_CHROMIUM',
-      'GL_SCANOUT_CHROMIUM'
+      'GL_READ_WRITE_CHROMIUM',
     ],
   },
   'ValueBufferTarget': {
diff --git a/gpu/command_buffer/client/gles2_implementation.cc b/gpu/command_buffer/client/gles2_implementation.cc
index 984c483..f0e4e9b 100644
--- a/gpu/command_buffer/client/gles2_implementation.cc
+++ b/gpu/command_buffer/client/gles2_implementation.cc
@@ -5484,13 +5484,7 @@ bool ValidImageFormat(GLenum internalformat,
 }
 
 bool ValidImageUsage(GLenum usage) {
-  switch (usage) {
-    case GL_MAP_CHROMIUM:
-    case GL_SCANOUT_CHROMIUM:
-      return true;
-    default:
-      return false;
-  }
+  return usage == GL_READ_WRITE_CHROMIUM;
 }
 
 }  // namespace
diff --git a/gpu/command_buffer/client/gles2_implementation_unittest.cc b/gpu/command_buffer/client/gles2_implementation_unittest.cc
index 8ff533d..2eabd33 100644
--- a/gpu/command_buffer/client/gles2_implementation_unittest.cc
+++ b/gpu/command_buffer/client/gles2_implementation_unittest.cc
@@ -4111,7 +4111,8 @@ TEST_F(GLES2ImplementationManualInitTest, LoseContextOnOOM) {
   GLsizei max = std::numeric_limits<GLsizei>::max();
   EXPECT_CALL(*gpu_control_, CreateGpuMemoryBufferImage(max, max, _, _))
       .WillOnce(Return(-1));
-  gl_->CreateGpuMemoryBufferImageCHROMIUM(max, max, GL_RGBA, GL_MAP_CHROMIUM);
+  gl_->CreateGpuMemoryBufferImageCHROMIUM(max, max, GL_RGBA,
+                                          GL_READ_WRITE_CHROMIUM);
   // The context should be lost.
   Cmds expected;
   expected.cmd.Init(GL_GUILTY_CONTEXT_RESET_ARB, GL_UNKNOWN_CONTEXT_RESET_ARB);
@@ -4129,7 +4130,8 @@ TEST_F(GLES2ImplementationManualInitTest, NoLoseContextOnOOM) {
   GLsizei max = std::numeric_limits<GLsizei>::max();
   EXPECT_CALL(*gpu_control_, CreateGpuMemoryBufferImage(max, max, _, _))
       .WillOnce(Return(-1));
-  gl_->CreateGpuMemoryBufferImageCHROMIUM(max, max, GL_RGBA, GL_MAP_CHROMIUM);
+  gl_->CreateGpuMemoryBufferImageCHROMIUM(max, max, GL_RGBA,
+                                          GL_READ_WRITE_CHROMIUM);
   // The context should not be lost.
   EXPECT_TRUE(NoCommandsWritten());
 }
diff --git a/gpu/command_buffer/common/gles2_cmd_utils_implementation_autogen.h b/gpu/command_buffer/common/gles2_cmd_utils_implementation_autogen.h
index 82c83fa..ba69729 100644
--- a/gpu/command_buffer/common/gles2_cmd_utils_implementation_autogen.h
+++ b/gpu/command_buffer/common/gles2_cmd_utils_implementation_autogen.h
@@ -97,7 +97,7 @@ static const GLES2Util::EnumToString enum_to_string_table[] = {
         0x9500, "GL_PERFQUERY_GPA_EXTENDED_COUNTERS_INTEL",
     },
     {
-        0x78F2, "GL_SCANOUT_CHROMIUM",
+        0x78F2, "GL_READ_WRITE_CHROMIUM",
     },
     {
         0x9138, "GL_COMPRESSED_RGBA_PVRTC_4BPPV2_IMG",
@@ -1906,7 +1906,7 @@ static const GLES2Util::EnumToString enum_to_string_table[] = {
         0x84CA, "GL_TEXTURE10",
     },
     {
-        0x78F1, "GL_MAP_CHROMIUM",
+        0x0BA7, "GL_PATH_PROJECTION_MATRIX_CHROMIUM",
     },
     {
         0x84CF, "GL_TEXTURE15",
@@ -2752,9 +2752,6 @@ static const GLES2Util::EnumToString enum_to_string_table[] = {
         0x8A2A, "GL_UNIFORM_BUFFER_SIZE",
     },
     {
-        0x0BA7, "GL_PATH_PROJECTION_MATRIX_CHROMIUM",
-    },
-    {
         0x0DE1, "GL_TEXTURE_2D",
     },
     {
@@ -3925,8 +3922,7 @@ std::string GLES2Util::GetStringImageInternalFormat(uint32_t value) {
 
 std::string GLES2Util::GetStringImageUsage(uint32_t value) {
   static const EnumToString string_table[] = {
-      {GL_MAP_CHROMIUM, "GL_MAP_CHROMIUM"},
-      {GL_SCANOUT_CHROMIUM, "GL_SCANOUT_CHROMIUM"},
+      {GL_READ_WRITE_CHROMIUM, "GL_READ_WRITE_CHROMIUM"},
   };
   return GLES2Util::GetQualifiedEnumString(string_table,
                                            arraysize(string_table), value);
diff --git a/gpu/command_buffer/service/gles2_cmd_validation_implementation_autogen.h b/gpu/command_buffer/service/gles2_cmd_validation_implementation_autogen.h
index aa05581..4f75b7d 100644
--- a/gpu/command_buffer/service/gles2_cmd_validation_implementation_autogen.h
+++ b/gpu/command_buffer/service/gles2_cmd_validation_implementation_autogen.h
@@ -367,7 +367,7 @@ static const GLenum valid_image_internal_format_table[] = {
 };
 
 static const GLenum valid_image_usage_table[] = {
-    GL_MAP_CHROMIUM, GL_SCANOUT_CHROMIUM,
+    GL_READ_WRITE_CHROMIUM,
 };
 
 static const GLenum valid_index_type_table[] = {
diff --git a/gpu/command_buffer/service/image_factory.cc b/gpu/command_buffer/service/image_factory.cc
index 2a1257e..bcfd121 100644
--- a/gpu/command_buffer/service/image_factory.cc
+++ b/gpu/command_buffer/service/image_factory.cc
@@ -48,20 +48,6 @@ gfx::BufferFormat ImageFactory::DefaultBufferFormatForImageFormat(
 }
 
 // static
-gfx::BufferUsage ImageFactory::ImageUsageToGpuMemoryBufferUsage(
-    unsigned usage) {
-  switch (usage) {
-    case GL_MAP_CHROMIUM:
-      return gfx::BufferUsage::MAP;
-    case GL_SCANOUT_CHROMIUM:
-      return gfx::BufferUsage::SCANOUT;
-    default:
-      NOTREACHED();
-      return gfx::BufferUsage::MAP;
-  }
-}
-
-// static
 bool ImageFactory::IsImageFormatCompatibleWithGpuMemoryBufferFormat(
     unsigned internalformat,
     gfx::BufferFormat format) {
diff --git a/gpu/command_buffer/service/image_factory.h b/gpu/command_buffer/service/image_factory.h
index c805db0..3746d56 100644
--- a/gpu/command_buffer/service/image_factory.h
+++ b/gpu/command_buffer/service/image_factory.h
@@ -26,10 +26,6 @@ class GPU_EXPORT ImageFactory {
   static gfx::BufferFormat DefaultBufferFormatForImageFormat(
       unsigned internalformat);
 
-  // Returns a valid GpuMemoryBuffer usage given a valid usage as defined by
-  // CHROMIUM_gpu_memory_buffer_image.
-  static gfx::BufferUsage ImageUsageToGpuMemoryBufferUsage(unsigned usage);
-
   // Returns true if |internalformat| is compatible with |format|.
   static bool IsImageFormatCompatibleWithGpuMemoryBufferFormat(
       unsigned internalformat,
diff --git a/gpu/command_buffer/service/in_process_command_buffer.cc b/gpu/command_buffer/service/in_process_command_buffer.cc
index 51b0b0a..5493054 100644
--- a/gpu/command_buffer/service/in_process_command_buffer.cc
+++ b/gpu/command_buffer/service/in_process_command_buffer.cc
@@ -778,7 +778,7 @@ int32 InProcessCommandBuffer::CreateGpuMemoryBufferImage(
       gpu_memory_buffer_manager_->AllocateGpuMemoryBuffer(
           gfx::Size(width, height),
           gpu::ImageFactory::DefaultBufferFormatForImageFormat(internalformat),
-          gpu::ImageFactory::ImageUsageToGpuMemoryBufferUsage(usage)));
+          gfx::BufferUsage::GPU_READ_WRITE));
   if (!buffer)
     return -1;
 
diff --git a/gpu/command_buffer/tests/gl_manager.cc b/gpu/command_buffer/tests/gl_manager.cc
index 9bb2a68..4daa466 100644
--- a/gpu/command_buffer/tests/gl_manager.cc
+++ b/gpu/command_buffer/tests/gl_manager.cc
@@ -450,7 +450,7 @@ int32 GLManager::CreateGpuMemoryBufferImage(size_t width,
                                             size_t height,
                                             unsigned internalformat,
                                             unsigned usage) {
-  DCHECK_EQ(usage, static_cast<unsigned>(GL_MAP_CHROMIUM));
+  DCHECK_EQ(usage, static_cast<unsigned>(GL_READ_WRITE_CHROMIUM));
   scoped_ptr<gfx::GpuMemoryBuffer> buffer = GLManager::CreateGpuMemoryBuffer(
       gfx::Size(width, height), gfx::BufferFormat::RGBA_8888);
   return CreateImage(buffer->AsClientBuffer(), width, height, internalformat);