Remove WebGL CHROMIUM image fallback logic.

third_party/WebKit/Source/platform/graphics/gpu/DrawingBuffer.cpp

 /*
  * Copyright (c) 2010, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 197 matching lines @@
 {
     return !m_drawFramebufferBinding && defaultBufferRequiresAlphaChannelToBePreserved();
 }
 
 bool DrawingBuffer::defaultBufferRequiresAlphaChannelToBePreserved()
 {
     if (wantExplicitResolve()) {
         return !m_wantAlphaChannel && getMultisampledRenderbufferFormat() == GL_RGBA8_OES;
     }
 
-    return !m_wantAlphaChannel && m_colorBuffer.imageId && contextProvider()->getCapabilities().chromium_image_rgb_emulation;
+    return !m_wantAlphaChannel && RuntimeEnabledFeatures::webGLImageChromiumEnabled() && contextProvider()->getCapabilities().chromium_image_rgb_emulation;
 }
 
 void DrawingBuffer::freeRecycledMailboxes()
 {
     if (m_recycledMailboxQueue.isEmpty())
         return;
     while (!m_recycledMailboxQueue.isEmpty())
         deleteMailbox(m_recycledMailboxQueue.takeLast());
 }
 
@@ skipping 728 matching lines @@
     restoreFramebufferBindings();
     m_gl->ClearColor(m_clearColor[0], m_clearColor[1], m_clearColor[2], m_clearColor[3]);
     m_gl->ColorMask(m_colorMask[0], m_colorMask[1], m_colorMask[2], m_colorMask[3]);
 }
 
 DrawingBuffer::TextureInfo DrawingBuffer::createTextureAndAllocateMemory(const IntSize& size)
 {
     if (!RuntimeEnabledFeatures::webGLImageChromiumEnabled())
         return createDefaultTextureAndAllocateMemory(size);
 
-    // First, try to allocate a CHROMIUM_image. This always has the potential to
-    // fail.
     TextureParameters parameters = chromiumImageTextureParameters();
     GLuint imageId = m_gl->CreateGpuMemoryBufferImageCHROMIUM(size.width(), size.height(), parameters.creationInternalColorFormat, GC3D_SCANOUT_CHROMIUM);
-    if (!imageId)
-        return createDefaultTextureAndAllocateMemory(size);
+    GLint gpuMemoryBufferId = -1;
+    GLuint textureId = createColorTexture(parameters);
 
-    GLuint textureId = createColorTexture(parameters);
-    m_gl->BindTexImage2DCHROMIUM(parameters.target, imageId);
-    GLint gpuMemoryBufferId = -1;
-    m_gl->GetImageivCHROMIUM(imageId, GC3D_GPU_MEMORY_BUFFER_ID, &gpuMemoryBufferId);
-    DCHECK_NE(-1, gpuMemoryBufferId);
+    if (imageId) {
+        m_gl->BindTexImage2DCHROMIUM(parameters.target, imageId);
+        m_gl->GetImageivCHROMIUM(imageId, GC3D_GPU_MEMORY_BUFFER_ID, &gpuMemoryBufferId);
+        DCHECK_NE(-1, gpuMemoryBufferId);
+    }
 
     TextureInfo info;
     info.textureId = textureId;
     info.imageId = imageId;
     info.gpuMemoryBufferId = gpuMemoryBufferId;
     info.parameters = parameters;
     clearChromiumImageAlpha(info);
     return info;
 }
 
 DrawingBuffer::TextureInfo DrawingBuffer::createDefaultTextureAndAllocateMemory(const IntSize& size)
 {
     TextureParameters parameters = defaultTextureParameters();
     GLuint textureId = createColorTexture(parameters);
     texImage2DResourceSafe(parameters.target, 0, parameters.creationInternalColorFormat, size.width(), size.height(), 0, parameters.colorFormat, GL_UNSIGNED_BYTE);
 
     DrawingBuffer::TextureInfo info;
     info.textureId = textureId;
     info.parameters = parameters;
     return info;
 }
 
 void DrawingBuffer::resizeTextureMemory(TextureInfo* info, const IntSize& size)
 {
     ASSERT(info->textureId);
-    if (info->imageId) {
-        deleteChromiumImageForTexture(info);
-        info->imageId = m_gl->CreateGpuMemoryBufferImageCHROMIUM(size.width(), size.height(), info->parameters.creationInternalColorFormat, GC3D_SCANOUT_CHROMIUM);
-        if (info->imageId) {
-            m_gl->BindTexture(info->parameters.target, info->textureId);
-            m_gl->BindTexImage2DCHROMIUM(info->parameters.target, info->imageId);
-
-            GLint gpuMemoryBufferId = -1;
-            m_gl->GetImageivCHROMIUM(info->imageId, GC3D_GPU_MEMORY_BUFFER_ID, &gpuMemoryBufferId);
-            DCHECK_NE(-1, gpuMemoryBufferId);
-            info->gpuMemoryBufferId = gpuMemoryBufferId;
-
-            clearChromiumImageAlpha(*info);
-            return;
-        }
-
-        // If the desired texture target is different, there's no way to fall back
-        // to a non CHROMIUM_image texture.
-        if (chromiumImageTextureParameters().target != defaultTextureParameters().target)
-            return;
+    if (!RuntimeEnabledFeatures::webGLImageChromiumEnabled()) {
+        m_gl->BindTexture(info->parameters.target, info->textureId);
+        texImage2DResourceSafe(info->parameters.target, 0, info->parameters.creationInternalColorFormat, size.width(), size.height(), 0, info->parameters.colorFormat, GL_UNSIGNED_BYTE);
+        return;
     }
 
-    m_gl->BindTexture(info->parameters.target, info->textureId);
-    texImage2DResourceSafe(info->parameters.target, 0, info->parameters.creationInternalColorFormat, size.width(), size.height(), 0, info->parameters.colorFormat, GL_UNSIGNED_BYTE);
+    deleteChromiumImageForTexture(info);
+    info->imageId = m_gl->CreateGpuMemoryBufferImageCHROMIUM(size.width(), size.height(), info->parameters.creationInternalColorFormat, GC3D_SCANOUT_CHROMIUM);
+    if (info->imageId) {
+        m_gl->BindTexture(info->parameters.target, info->textureId);
+        m_gl->BindTexImage2DCHROMIUM(info->parameters.target, info->imageId);
+
+        GLint gpuMemoryBufferId = -1;
+        m_gl->GetImageivCHROMIUM(info->imageId, GC3D_GPU_MEMORY_BUFFER_ID, &gpuMemoryBufferId);
+        DCHECK_NE(-1, gpuMemoryBufferId);
+        info->gpuMemoryBufferId = gpuMemoryBufferId;
+
+        clearChromiumImageAlpha(*info);
+    } else {
+        info->gpuMemoryBufferId = -1;
+
+        // At this point, the texture still exists, but has no allocated
+        // storage. This is intentional, and mimics the behavior of a texImage2D
+        // failure.
+    }
 }
 
 void DrawingBuffer::attachColorBufferToReadFramebuffer()
 {
     m_gl->BindFramebuffer(GL_FRAMEBUFFER, m_fbo);
 
     GLenum target = m_colorBuffer.parameters.target;
     GLenum id = m_colorBuffer.textureId;
 
     m_gl->BindTexture(target, id);
@@ skipping 15 matching lines @@
 bool DrawingBuffer::wantDepthOrStencil()
 {
     return m_wantDepth || m_wantStencil;
 }
 
 GLenum DrawingBuffer::getMultisampledRenderbufferFormat()
 {
     DCHECK(wantExplicitResolve());
     if (m_wantAlphaChannel)
         return GL_RGBA8_OES;
-    if (m_colorBuffer.imageId && contextProvider()->getCapabilities().chromium_image_rgb_emulation)
+    if (RuntimeEnabledFeatures::webGLImageChromiumEnabled() && contextProvider()->getCapabilities().chromium_image_rgb_emulation)
         return GL_RGBA8_OES;
     return GL_RGB8_OES;
 }
 
 void DrawingBuffer::restoreTextureBindings()
 {
     // This class potentially modifies the bindings for GL_TEXTURE_2D and
     // GL_TEXTURE_RECTANGLE. Only GL_TEXTURE_2D needs to be restored since
     // the public interface for WebGL does not support GL_TEXTURE_RECTANGLE.
     m_gl->BindTexture(GL_TEXTURE_2D, m_texture2DBinding);
 }
 
 } // namespace blink