Removed arbitrary 4096 size limit on WebGL canvas backbuffers, Take 2

Source/platform/graphics/gpu/DrawingBuffer.cpp

Index: Source/platform/graphics/gpu/DrawingBuffer.cpp
diff --git a/Source/platform/graphics/gpu/DrawingBuffer.cpp b/Source/platform/graphics/gpu/DrawingBuffer.cpp
index aa528a3b761c82c8ed8dd9b4e8eaa86145009398..921199de031989157712021ea049004b5a7385ea 100644
--- a/Source/platform/graphics/gpu/DrawingBuffer.cpp
+++ b/Source/platform/graphics/gpu/DrawingBuffer.cpp
@@ -620,7 +620,8 @@ bool DrawingBuffer::resizeFramebuffer(const IntSize& size)
 
     m_context->bindTexture(GL_TEXTURE_2D, m_colorBuffer.textureId);
 
-    allocateTextureMemory(&m_colorBuffer, size);
+    if (!allocateTextureMemory(&m_colorBuffer, size))
+        return false;
 
     if (m_multisampleMode == ImplicitResolve)
         m_context->framebufferTexture2DMultisampleEXT(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, m_colorBuffer.textureId, 0, m_sampleCount);
@@ -629,8 +630,10 @@ bool DrawingBuffer::resizeFramebuffer(const IntSize& size)
 
     m_context->bindTexture(GL_TEXTURE_2D, 0);
 
-    if (m_multisampleMode != ExplicitResolve)
-        resizeDepthStencil(size);
+    if (m_multisampleMode != ExplicitResolve) {
+        if (!resizeDepthStencil(size))
+            return false;
+    }
     if (m_context->checkFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
         return false;
 
@@ -649,7 +652,8 @@ bool DrawingBuffer::resizeMultisampleFramebuffer(const IntSize& size)
             return false;
 
         m_context->framebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, m_multisampleColorBuffer);
-        resizeDepthStencil(size);
+        if (!resizeDepthStencil(size))
+            return false;
         if (m_context->checkFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
             return false;
     }
@@ -657,10 +661,10 @@ bool DrawingBuffer::resizeMultisampleFramebuffer(const IntSize& size)
     return true;
 }
 
-void DrawingBuffer::resizeDepthStencil(const IntSize& size)
+bool DrawingBuffer::resizeDepthStencil(const IntSize& size)
 {
     if (!m_requestedAttributes.depth && !m_requestedAttributes.stencil)
-        return;
+        return true;
 
     if (m_packedDepthStencilExtensionSupported) {
         if (!m_depthStencilBuffer)
@@ -701,6 +705,11 @@ void DrawingBuffer::resizeDepthStencil(const IntSize& size)
         }
     }
     m_context->bindRenderbuffer(GL_RENDERBUFFER, 0);
+
+    if (m_context->getError() == GL_OUT_OF_MEMORY)
+        return false;

[Ken Russell (switch to Gerrit), 2015/03/31 02:13:33]

There's a preexisting bug with all of the getError() calls in this file. If it
happened that the user caused a GL error then these checks may return the other
error and miss the out-of-memory error.

In order to fix this, the m_lostContextErrors in WebGLRenderingContextBase
should be generalized to be used all the time, and a method for copying the
"real" GL errors from the WebGraphicsContext3D into it should be added. Then
before WebGLRenderingContextBase calls into DrawingBuffer, the
WebGLRenderingContextBase should copy the real errors into itself. Care is
needed to watch out for lost contexts.

Would you either add this mechanism in this CL or file a bug about doing so?
Thanks.

+
+    return true;
 }
 
 
@@ -963,19 +972,28 @@ void DrawingBuffer::texImage2DResourceSafe(GLenum target, GLint level, GLenum in
     m_context->texImage2D(target, level, internalformat, width, height, border, format, type, 0);
 }
 
-void DrawingBuffer::allocateTextureMemory(TextureInfo* info, const IntSize& size)
+bool DrawingBuffer::allocateTextureMemory(TextureInfo* info, const IntSize& size)
 {
     if (RuntimeEnabledFeatures::webGLImageChromiumEnabled()) {
         deleteChromiumImageForTexture(info);
 
         info->imageId = m_context->createGpuMemoryBufferImageCHROMIUM(size.width(), size.height(), GL_RGBA, GC3D_SCANOUT_CHROMIUM);
+
+        if (m_context->getError() == GL_OUT_OF_MEMORY)
+            return false;
+
         if (info->imageId) {
             m_context->bindTexImage2DCHROMIUM(GL_TEXTURE_2D, info->imageId);
-            return;
+            return true;
         }
     }
 
     texImage2DResourceSafe(GL_TEXTURE_2D, 0, m_internalColorFormat, size.width(), size.height(), 0, m_colorFormat, GL_UNSIGNED_BYTE);
+
+    if (m_context->getError() == GL_OUT_OF_MEMORY)
+        return false;
+
+    return true;
 }
 
 void DrawingBuffer::deleteChromiumImageForTexture(TextureInfo* info)