Add a command to lose the context

BUG=166020


Review URL: https://chromiumcodereview.appspot.com/11568029

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@173441 0039d316-1c4b-4281-b951-d872f2087c98

37 files changed, 411 insertions, 40 deletions

diff --git a/gpu/GLES2/extensions/CHROMIUM/CHROMIUM_lose_context.txt b/gpu/GLES2/extensions/CHROMIUM/CHROMIUM_lose_context.txt
new file mode 100644
index 0000000..a7ff30c
--- /dev/null
+++ b/gpu/GLES2/extensions/CHROMIUM/CHROMIUM_lose_context.txt
@@ -0,0 +1,55 @@
+Name
+
+    CHROMIUM_lose_context
+
+Name Strings
+
+    GL_CHROMIUM_lose_context
+
+Version
+
+    Last Modifed Date: December 17, 2012
+
+Dependencies
+
+    OpenGL ES 2.0 is required.
+
+Overview
+
+    This extension allows an application to force a lost context event.
+    This is useful for debugging that an app can correctly handle the context
+    becoming lost.
+
+Issues
+
+    None
+
+New Tokens
+
+    None
+
+New Procedures and Functions
+
+    void LoseContextCHROMIUM (GLenum current, GLenum other)
+
+    Causes the current context and all other contexts in the same share group
+    to become lost. <current> and <other> can each be one of:
+
+        GL_GUILTY_CONTEXT_RESET_EXT
+        GL_INNOCENT_CONTEXT_RESET_EXT
+        GL_UNKNOWN_CONTEXT_RESET_EXT
+
+    INVALID_ENUM is generated if <current> or <other> is not one of the values
+    mentioned above.
+
+Errors
+
+    None.
+
+New State
+
+    None.
+
+Revision History
+
+    12/17/2012    Documented the extension
diff --git a/gpu/GLES2/gl2chromium.h b/gpu/GLES2/gl2chromium.h
index 8598052..7cc84f0 100644
--- a/gpu/GLES2/gl2chromium.h
+++ b/gpu/GLES2/gl2chromium.h
@@ -227,6 +227,7 @@
 #define glAsyncTexSubImage2DCHROMIUM GLES2_GET_FUN(AsyncTexSubImage2DCHROMIUM)
 #define glAsyncTexImage2DCHROMIUM GLES2_GET_FUN(AsyncTexImage2DCHROMIUM)
 #define glDiscardFramebufferEXT GLES2_GET_FUN(DiscardFramebufferEXT)
+#define glLoseContextCHROMIUM GLES2_GET_FUN(LoseContextCHROMIUM)
 
 #endif  // GPU_GLES2_GL2CHROMIUM_H_
 
diff --git a/gpu/command_buffer/build_gles2_cmd_buffer.py b/gpu/command_buffer/build_gles2_cmd_buffer.py
index 8ea1d3c..9babf73 100755
--- a/gpu/command_buffer/build_gles2_cmd_buffer.py
+++ b/gpu/command_buffer/build_gles2_cmd_buffer.py
@@ -1114,6 +1114,14 @@ _ENUM_LISTS = {
       'true',
     ],
   },
+  'ResetStatus': {
+    'type': 'GLenum',
+    'valid': [
+      'GL_GUILTY_CONTEXT_RESET_ARB',
+      'GL_INNOCENT_CONTEXT_RESET_ARB',
+      'GL_UNKNOWN_CONTEXT_RESET_ARB',
+    ],
+  },
 }
 
 # This table specifies the different pepper interfaces that are supported for
@@ -2296,6 +2304,12 @@ _FUNCTION_INFO = {
     'client_test': False,
     'extension': True,
   },
+  'LoseContextCHROMIUM': {
+    'type': 'Manual',
+    'impl_func': True,
+    'extension': True,
+    'chromium': True,
+  },
 }
 
 
@@ -3354,7 +3368,8 @@ class ManualHandler(CustomHandler):
 
   def WriteGLES2Implementation(self, func, file):
     """Overrriden from TypeHandler."""
-    pass
+    if func.GetInfo('impl_func'):
+      super(ManualHandler, self).WriteGLES2Implementation(func, file)
 
   def WriteGLES2ImplementationHeader(self, func, file):
     """Overrriden from TypeHandler."""
diff --git a/gpu/command_buffer/client/gles2_c_lib_autogen.h b/gpu/command_buffer/client/gles2_c_lib_autogen.h
index b4d8e0f..dff3135 100644
--- a/gpu/command_buffer/client/gles2_c_lib_autogen.h
+++ b/gpu/command_buffer/client/gles2_c_lib_autogen.h
@@ -715,6 +715,9 @@ void GLES2DiscardFramebufferEXT(
     GLenum target, GLsizei count, const GLenum* attachments) {
   gles2::GetGLContext()->DiscardFramebufferEXT(target, count, attachments);
 }
+void GLES2LoseContextCHROMIUM(GLenum current, GLenum other) {
+  gles2::GetGLContext()->LoseContextCHROMIUM(current, other);
+}
 
 namespace gles2 {
 
@@ -1048,6 +1051,8 @@ NameToFunc g_gles2_function_table[] = {
       glAsyncTexImage2DCHROMIUM), },
   { "glDiscardFramebufferEXT", reinterpret_cast<GLES2FunctionPointer>(
       glDiscardFramebufferEXT), },
+  { "glLoseContextCHROMIUM", reinterpret_cast<GLES2FunctionPointer>(
+      glLoseContextCHROMIUM), },
   { NULL, NULL, },
 };
 
diff --git a/gpu/command_buffer/client/gles2_cmd_helper_autogen.h b/gpu/command_buffer/client/gles2_cmd_helper_autogen.h
index 66a5c8a5..18cf105 100644
--- a/gpu/command_buffer/client/gles2_cmd_helper_autogen.h
+++ b/gpu/command_buffer/client/gles2_cmd_helper_autogen.h
@@ -1980,5 +1980,12 @@
     }
   }
 
+  void LoseContextCHROMIUM(GLenum current, GLenum other) {
+    gles2::LoseContextCHROMIUM* c = GetCmdSpace<gles2::LoseContextCHROMIUM>();
+    if (c) {
+      c->Init(current, other);
+    }
+  }
+
 #endif  // GPU_COMMAND_BUFFER_CLIENT_GLES2_CMD_HELPER_AUTOGEN_H_
 
diff --git a/gpu/command_buffer/client/gles2_implementation_autogen.h b/gpu/command_buffer/client/gles2_implementation_autogen.h
index b0ed75f..efaaa28 100644
--- a/gpu/command_buffer/client/gles2_implementation_autogen.h
+++ b/gpu/command_buffer/client/gles2_implementation_autogen.h
@@ -522,5 +522,7 @@ virtual void AsyncTexImage2DCHROMIUM(
 virtual void DiscardFramebufferEXT(
     GLenum target, GLsizei count, const GLenum* attachments) OVERRIDE;
 
+virtual void LoseContextCHROMIUM(GLenum current, GLenum other) OVERRIDE;
+
 #endif  // GPU_COMMAND_BUFFER_CLIENT_GLES2_IMPLEMENTATION_AUTOGEN_H_
 
diff --git a/gpu/command_buffer/client/gles2_implementation_impl_autogen.h b/gpu/command_buffer/client/gles2_implementation_impl_autogen.h
index 57aa0cd..0fc3a4d 100644
--- a/gpu/command_buffer/client/gles2_implementation_impl_autogen.h
+++ b/gpu/command_buffer/client/gles2_implementation_impl_autogen.h
@@ -1696,5 +1696,12 @@ void GLES2Implementation::DiscardFramebufferEXT(
   CheckGLError();
 }
 
+void GLES2Implementation::LoseContextCHROMIUM(GLenum current, GLenum other) {
+  GPU_CLIENT_SINGLE_THREAD_CHECK();
+  GPU_CLIENT_LOG("[" << GetLogPrefix() << "] glLoseContextCHROMIUM(" << GLES2Util::GetStringEnum(current) << ", " << GLES2Util::GetStringEnum(other) << ")");  // NOLINT
+  helper_->LoseContextCHROMIUM(current, other);
+  CheckGLError();
+}
+
 #endif  // GPU_COMMAND_BUFFER_CLIENT_GLES2_IMPLEMENTATION_IMPL_AUTOGEN_H_
 
diff --git a/gpu/command_buffer/client/gles2_implementation_unittest_autogen.h b/gpu/command_buffer/client/gles2_implementation_unittest_autogen.h
index f23a512..2de2e54 100644
--- a/gpu/command_buffer/client/gles2_implementation_unittest_autogen.h
+++ b/gpu/command_buffer/client/gles2_implementation_unittest_autogen.h
@@ -1786,5 +1786,16 @@ TEST_F(GLES2ImplementationTest, DiscardFramebufferEXT) {
   gl_->DiscardFramebufferEXT(1, 2, &expected.data[0][0]);
   EXPECT_EQ(0, memcmp(&expected, commands_, sizeof(expected)));
 }
+
+TEST_F(GLES2ImplementationTest, LoseContextCHROMIUM) {
+  struct Cmds {
+    LoseContextCHROMIUM cmd;
+  };
+  Cmds expected;
+  expected.cmd.Init(1, 2);
+
+  gl_->LoseContextCHROMIUM(1, 2);
+  EXPECT_EQ(0, memcmp(&expected, commands_, sizeof(expected)));
+}
 #endif  // GPU_COMMAND_BUFFER_CLIENT_GLES2_IMPLEMENTATION_UNITTEST_AUTOGEN_H_
 
diff --git a/gpu/command_buffer/client/gles2_interface_autogen.h b/gpu/command_buffer/client/gles2_interface_autogen.h
index 163361d..f295bdf 100644
--- a/gpu/command_buffer/client/gles2_interface_autogen.h
+++ b/gpu/command_buffer/client/gles2_interface_autogen.h
@@ -301,5 +301,6 @@ virtual void AsyncTexImage2DCHROMIUM(
     const void* pixels) = 0;
 virtual void DiscardFramebufferEXT(
     GLenum target, GLsizei count, const GLenum* attachments) = 0;
+virtual void LoseContextCHROMIUM(GLenum current, GLenum other) = 0;
 #endif  // GPU_COMMAND_BUFFER_CLIENT_GLES2_INTERFACE_AUTOGEN_H_
 
diff --git a/gpu/command_buffer/client/gles2_interface_stub_autogen.h b/gpu/command_buffer/client/gles2_interface_stub_autogen.h
index f3d51d8..80e5607 100644
--- a/gpu/command_buffer/client/gles2_interface_stub_autogen.h
+++ b/gpu/command_buffer/client/gles2_interface_stub_autogen.h
@@ -333,5 +333,6 @@ virtual void AsyncTexImage2DCHROMIUM(
     const void* pixels) OVERRIDE;
 virtual void DiscardFramebufferEXT(
     GLenum target, GLsizei count, const GLenum* attachments) OVERRIDE;
+virtual void LoseContextCHROMIUM(GLenum current, GLenum other) OVERRIDE;
 #endif  // GPU_COMMAND_BUFFER_CLIENT_GLES2_INTERFACE_STUB_AUTOGEN_H_
 
diff --git a/gpu/command_buffer/client/gles2_interface_stub_impl_autogen.h b/gpu/command_buffer/client/gles2_interface_stub_impl_autogen.h
index cf516e3..bc55938 100644
--- a/gpu/command_buffer/client/gles2_interface_stub_impl_autogen.h
+++ b/gpu/command_buffer/client/gles2_interface_stub_impl_autogen.h
@@ -627,5 +627,8 @@ void GLES2InterfaceStub::DiscardFramebufferEXT(
     GLenum /* target */, GLsizei /* count */,
     const GLenum* /* attachments */) {
 }
+void GLES2InterfaceStub::LoseContextCHROMIUM(
+    GLenum /* current */, GLenum /* other */) {
+}
 #endif  // GPU_COMMAND_BUFFER_CLIENT_GLES2_INTERFACE_STUB_IMPL_AUTOGEN_H_
 
diff --git a/gpu/command_buffer/cmd_buffer_functions.txt b/gpu/command_buffer/cmd_buffer_functions.txt
index fb53030..2664631 100644
--- a/gpu/command_buffer/cmd_buffer_functions.txt
+++ b/gpu/command_buffer/cmd_buffer_functions.txt
@@ -206,3 +206,6 @@ GL_APICALL void         GL_APIENTRY glTraceEndCHROMIUM (void);
 GL_APICALL void         GL_APIENTRY glAsyncTexSubImage2DCHROMIUM (GLenumTextureTarget target, GLint level, GLint xoffset, GLint yoffset, GLsizei width, GLsizei height, GLenumTextureFormat format, GLenumPixelType type, const void* data);
 GL_APICALL void         GL_APIENTRY glAsyncTexImage2DCHROMIUM (GLenumTextureTarget target, GLint level, GLintTextureInternalFormat internalformat, GLsizei width, GLsizei height, GLintTextureBorder border, GLenumTextureFormat format, GLenumPixelType type, const void* pixels);
 GL_APICALL void         GL_APIENTRY glDiscardFramebufferEXT (GLenum target, GLsizei count, const GLenum* attachments);
+GL_APICALL void         GL_APIENTRY glLoseContextCHROMIUM (GLenum current, GLenum other);
+
+
diff --git a/gpu/command_buffer/common/gles2_cmd_format_autogen.h b/gpu/command_buffer/common/gles2_cmd_format_autogen.h
index d7e887d..ca9c90b 100644
--- a/gpu/command_buffer/common/gles2_cmd_format_autogen.h
+++ b/gpu/command_buffer/common/gles2_cmd_format_autogen.h
@@ -10830,6 +10830,44 @@ COMPILE_ASSERT(offsetof(DiscardFramebufferEXTImmediate, target) == 4,
 COMPILE_ASSERT(offsetof(DiscardFramebufferEXTImmediate, count) == 8,
                OffsetOf_DiscardFramebufferEXTImmediate_count_not_8);
 
+struct LoseContextCHROMIUM {
+  typedef LoseContextCHROMIUM ValueType;
+  static const CommandId kCmdId = kLoseContextCHROMIUM;
+  static const cmd::ArgFlags kArgFlags = cmd::kFixed;
+
+  static uint32 ComputeSize() {
+    return static_cast<uint32>(sizeof(ValueType));  // NOLINT
+  }
+
+  void SetHeader() {
+    header.SetCmd<ValueType>();
+  }
+
+  void Init(GLenum _current, GLenum _other) {
+    SetHeader();
+    current = _current;
+    other = _other;
+  }
+
+  void* Set(void* cmd, GLenum _current, GLenum _other) {
+    static_cast<ValueType*>(cmd)->Init(_current, _other);
+    return NextCmdAddress<ValueType>(cmd);
+  }
+
+  gpu::CommandHeader header;
+  uint32 current;
+  uint32 other;
+};
+
+COMPILE_ASSERT(sizeof(LoseContextCHROMIUM) == 12,
+               Sizeof_LoseContextCHROMIUM_is_not_12);
+COMPILE_ASSERT(offsetof(LoseContextCHROMIUM, header) == 0,
+               OffsetOf_LoseContextCHROMIUM_header_not_0);
+COMPILE_ASSERT(offsetof(LoseContextCHROMIUM, current) == 4,
+               OffsetOf_LoseContextCHROMIUM_current_not_4);
+COMPILE_ASSERT(offsetof(LoseContextCHROMIUM, other) == 8,
+               OffsetOf_LoseContextCHROMIUM_other_not_8);
+
 
 #endif  // GPU_COMMAND_BUFFER_COMMON_GLES2_CMD_FORMAT_AUTOGEN_H_
 
diff --git a/gpu/command_buffer/common/gles2_cmd_format_test_autogen.h b/gpu/command_buffer/common/gles2_cmd_format_test_autogen.h
index 54795a7..80a2768 100644
--- a/gpu/command_buffer/common/gles2_cmd_format_test_autogen.h
+++ b/gpu/command_buffer/common/gles2_cmd_format_test_autogen.h
@@ -4364,5 +4364,20 @@ TEST_F(GLES2FormatTest, DiscardFramebufferEXTImmediate) {
   // TODO(gman): Check that data was inserted;
 }
 
+TEST_F(GLES2FormatTest, LoseContextCHROMIUM) {
+  LoseContextCHROMIUM& cmd = *GetBufferAs<LoseContextCHROMIUM>();
+  void* next_cmd = cmd.Set(
+      &cmd,
+      static_cast<GLenum>(11),
+      static_cast<GLenum>(12));
+  EXPECT_EQ(static_cast<uint32>(LoseContextCHROMIUM::kCmdId),
+            cmd.header.command);
+  EXPECT_EQ(sizeof(cmd), cmd.header.size * 4u);
+  EXPECT_EQ(static_cast<GLenum>(11), cmd.current);
+  EXPECT_EQ(static_cast<GLenum>(12), cmd.other);
+  CheckBytesWrittenMatchesExpectedSize(
+      next_cmd, sizeof(cmd));
+}
+
 #endif  // GPU_COMMAND_BUFFER_COMMON_GLES2_CMD_FORMAT_TEST_AUTOGEN_H_
 
diff --git a/gpu/command_buffer/common/gles2_cmd_ids_autogen.h b/gpu/command_buffer/common/gles2_cmd_ids_autogen.h
index 0a7a577..13f6170 100644
--- a/gpu/command_buffer/common/gles2_cmd_ids_autogen.h
+++ b/gpu/command_buffer/common/gles2_cmd_ids_autogen.h
@@ -247,6 +247,7 @@
   OP(AsyncTexImage2DCHROMIUM)                                  /* 490 */ \
   OP(DiscardFramebufferEXT)                                    /* 491 */ \
   OP(DiscardFramebufferEXTImmediate)                           /* 492 */ \
+  OP(LoseContextCHROMIUM)                                      /* 493 */ \
 
 enum CommandId {
   kStartPoint = cmd::kLastCommonId,  // All GLES2 commands start after this.
diff --git a/gpu/command_buffer/common/gles2_cmd_utils_autogen.h b/gpu/command_buffer/common/gles2_cmd_utils_autogen.h
index 944c16f..00e1f0ea 100644
--- a/gpu/command_buffer/common/gles2_cmd_utils_autogen.h
+++ b/gpu/command_buffer/common/gles2_cmd_utils_autogen.h
@@ -42,6 +42,7 @@ static std::string GetStringReadPixelType(uint32 value);
 static std::string GetStringRenderBufferFormat(uint32 value);
 static std::string GetStringRenderBufferParameter(uint32 value);
 static std::string GetStringRenderBufferTarget(uint32 value);
+static std::string GetStringResetStatus(uint32 value);
 static std::string GetStringShaderBinaryFormat(uint32 value);
 static std::string GetStringShaderParameter(uint32 value);
 static std::string GetStringShaderPrecision(uint32 value);
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 332d321..447efff 100644
--- a/gpu/command_buffer/common/gles2_cmd_utils_implementation_autogen.h
+++ b/gpu/command_buffer/common/gles2_cmd_utils_implementation_autogen.h
@@ -1134,6 +1134,16 @@ std::string GLES2Util::GetStringRenderBufferTarget(uint32 value) {
       string_table, arraysize(string_table), value);
 }
 
+std::string GLES2Util::GetStringResetStatus(uint32 value) {
+  static EnumToString string_table[] = {
+    { GL_GUILTY_CONTEXT_RESET_ARB, "GL_GUILTY_CONTEXT_RESET_ARB" },
+    { GL_INNOCENT_CONTEXT_RESET_ARB, "GL_INNOCENT_CONTEXT_RESET_ARB" },
+    { GL_UNKNOWN_CONTEXT_RESET_ARB, "GL_UNKNOWN_CONTEXT_RESET_ARB" },
+  };
+  return GLES2Util::GetQualifiedEnumString(
+      string_table, arraysize(string_table), value);
+}
+
 std::string GLES2Util::GetStringShaderBinaryFormat(uint32 value) {
   return GLES2Util::GetQualifiedEnumString(
       NULL, 0, value);
diff --git a/gpu/command_buffer/service/context_group.cc b/gpu/command_buffer/service/context_group.cc
index d8487c7..abf262d 100644
--- a/gpu/command_buffer/service/context_group.cc
+++ b/gpu/command_buffer/service/context_group.cc
@@ -36,7 +36,6 @@ ContextGroup::ContextGroup(
     : mailbox_manager_(mailbox_manager ? mailbox_manager : new MailboxManager),
       image_manager_(image_manager ? image_manager : new ImageManager),
       memory_tracker_(memory_tracker),
-      num_contexts_(0),
       enforce_gl_minimums_(CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kEnforceGLMinimums)),
       bind_generates_resource_(bind_generates_resource),
@@ -71,10 +70,13 @@ static void GetIntegerv(GLenum pname, uint32* var) {
   *var = value;
 }
 
-bool ContextGroup::Initialize(const DisallowedFeatures& disallowed_features,
-                              const char* allowed_features) {
-  if (num_contexts_ > 0) {
-    ++num_contexts_;
+bool ContextGroup::Initialize(
+    GLES2Decoder* decoder,
+    const DisallowedFeatures& disallowed_features,
+    const char* allowed_features) {
+  // If we've already initialized the group just add the context.
+  if (HaveContexts()) {
+    decoders_.push_back(base::AsWeakPtr<GLES2Decoder>(decoder));
     return true;
   }
 
@@ -201,14 +203,31 @@ bool ContextGroup::Initialize(const DisallowedFeatures& disallowed_features,
     return false;
   }
 
-  ++num_contexts_;
+  decoders_.push_back(base::AsWeakPtr<GLES2Decoder>(decoder));
   return true;
 }
 
-void ContextGroup::Destroy(bool have_context) {
-  DCHECK(num_contexts_ > 0);
-  if (--num_contexts_ > 0)
+namespace {
+
+bool IsNull(const base::WeakPtr<gles2::GLES2Decoder>& decoder) {
+  return !decoder;
+}
+
+}  // namespace anonymous
+
+bool ContextGroup::HaveContexts() {
+  decoders_.erase(std::remove_if(decoders_.begin(), decoders_.end(), IsNull),
+                  decoders_.end());
+  return !decoders_.empty();
+}
+
+void ContextGroup::Destroy(GLES2Decoder* decoder, bool have_context) {
+  decoders_.erase(std::remove(decoders_.begin(), decoders_.end(), decoder),
+                  decoders_.end());
+  // If we still have contexts do nothing.
+  if (HaveContexts()) {
     return;
+  }
 
   if (buffer_manager_ != NULL) {
     buffer_manager_->Destroy(have_context);
@@ -263,8 +282,16 @@ uint32 ContextGroup::GetMemRepresented() const {
   return total;
 }
 
+void ContextGroup::LoseContexts(GLenum reset_status) {
+  for (size_t ii = 0; ii < decoders_.size(); ++ii) {
+    if (decoders_[ii]) {
+      decoders_[ii]->LoseContext(reset_status);
+    }
+  }
+}
+
 ContextGroup::~ContextGroup() {
-  CHECK(num_contexts_ == 0);
+  CHECK(!HaveContexts());
 }
 
 bool ContextGroup::CheckGLFeature(GLint min_required, GLint* v) {
diff --git a/gpu/command_buffer/service/context_group.h b/gpu/command_buffer/service/context_group.h
index c459c56..064e36f 100644
--- a/gpu/command_buffer/service/context_group.h
+++ b/gpu/command_buffer/service/context_group.h
@@ -6,11 +6,13 @@
 #define GPU_COMMAND_BUFFER_SERVICE_CONTEXT_GROUP_H_
 
 #include <string>
+#include <vector>
 #include "base/basictypes.h"
 #include "base/hash_tables.h"
 #include "base/memory/linked_ptr.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
 #include "gpu/command_buffer/common/gles2_cmd_format.h"
 #include "gpu/command_buffer/service/gles2_cmd_validation.h"
 #include "gpu/command_buffer/service/feature_info.h"
@@ -50,12 +52,14 @@ class GPU_EXPORT ContextGroup : public base::RefCounted<ContextGroup> {
 
   // This should only be called by GLES2Decoder. This must be paired with a
   // call to destroy if it succeeds.
-  bool Initialize(const DisallowedFeatures& disallowed_features,
-                  const char* allowed_features);
+  bool Initialize(
+      GLES2Decoder* decoder,
+      const DisallowedFeatures& disallowed_features,
+      const char* allowed_features);
 
   // Destroys all the resources when called for the last context in the group.
   // It should only be called by GLES2Decoder.
-  void Destroy(bool have_context);
+  void Destroy(GLES2Decoder* decoder, bool have_context);
 
   MailboxManager* mailbox_manager() const {
     return mailbox_manager_.get();
@@ -145,6 +149,9 @@ class GPU_EXPORT ContextGroup : public base::RefCounted<ContextGroup> {
 
   uint32 GetMemRepresented() const;
 
+  // Loses all the context associated with this group.
+  void LoseContexts(GLenum reset_status);
+
  private:
   friend class base::RefCounted<ContextGroup>;
   ~ContextGroup();
@@ -153,14 +160,13 @@ class GPU_EXPORT ContextGroup : public base::RefCounted<ContextGroup> {
   bool CheckGLFeatureU(GLint min_required, uint32* v);
   bool QueryGLFeature(GLenum pname, GLint min_required, GLint* v);
   bool QueryGLFeatureU(GLenum pname, GLint min_required, uint32* v);
+  bool HaveContexts();
 
   scoped_refptr<MailboxManager> mailbox_manager_;
   scoped_refptr<ImageManager> image_manager_;
   scoped_refptr<MemoryTracker> memory_tracker_;
   scoped_ptr<TransferBufferManagerInterface> transfer_buffer_manager_;
 
-  // Whether or not this context is initialized.
-  int num_contexts_;
   bool enforce_gl_minimums_;
   bool bind_generates_resource_;
 
@@ -191,6 +197,8 @@ class GPU_EXPORT ContextGroup : public base::RefCounted<ContextGroup> {
 
   FeatureInfo::Ref feature_info_;
 
+  std::vector<base::WeakPtr<gles2::GLES2Decoder> > decoders_;
+
   DISALLOW_COPY_AND_ASSIGN(ContextGroup);
 };
 
diff --git a/gpu/command_buffer/service/context_group_unittest.cc b/gpu/command_buffer/service/context_group_unittest.cc
index 8ae1db3..983130f 100644
--- a/gpu/command_buffer/service/context_group_unittest.cc
+++ b/gpu/command_buffer/service/context_group_unittest.cc
@@ -5,6 +5,7 @@
 #include "gpu/command_buffer/service/context_group.h"
 
 #include "base/memory/scoped_ptr.h"
+#include "gpu/command_buffer/service/gles2_cmd_decoder_mock.h"
 #include "gpu/command_buffer/service/test_helper.h"
 #include "gpu/command_buffer/service/texture_manager.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ -36,6 +37,7 @@ class ContextGroupTest : public testing::Test {
   virtual void SetUp() {
     gl_.reset(new ::testing::StrictMock< ::gfx::MockGLInterface>());
     ::gfx::GLInterface::SetGLInterface(gl_.get());
+    decoder_.reset(new MockGLES2Decoder());
     group_ = ContextGroup::Ref(new ContextGroup(NULL, NULL, NULL, true));
   }
 
@@ -45,6 +47,7 @@ class ContextGroupTest : public testing::Test {
   }
 
   scoped_ptr< ::testing::StrictMock< ::gfx::MockGLInterface> > gl_;
+  scoped_ptr<MockGLES2Decoder> decoder_;
   ContextGroup::Ref group_;
 };
 
@@ -68,7 +71,7 @@ TEST_F(ContextGroupTest, Basic) {
 TEST_F(ContextGroupTest, InitializeNoExtensions) {
   TestHelper::SetupContextGroupInitExpectations(gl_.get(),
       DisallowedFeatures(), "");
-  group_->Initialize(DisallowedFeatures(), "");
+  group_->Initialize(decoder_.get(), DisallowedFeatures(), "");
   EXPECT_EQ(static_cast<uint32>(TestHelper::kNumVertexAttribs),
             group_->max_vertex_attribs());
   EXPECT_EQ(static_cast<uint32>(TestHelper::kNumTextureUnits),
@@ -90,7 +93,7 @@ TEST_F(ContextGroupTest, InitializeNoExtensions) {
   EXPECT_TRUE(group_->program_manager() != NULL);
   EXPECT_TRUE(group_->shader_manager() != NULL);
 
-  group_->Destroy(false);
+  group_->Destroy(decoder_.get(), false);
   EXPECT_TRUE(group_->buffer_manager() == NULL);
   EXPECT_TRUE(group_->framebuffer_manager() == NULL);
   EXPECT_TRUE(group_->renderbuffer_manager() == NULL);
@@ -100,10 +103,11 @@ TEST_F(ContextGroupTest, InitializeNoExtensions) {
 }
 
 TEST_F(ContextGroupTest, MultipleContexts) {
+  scoped_ptr<MockGLES2Decoder> decoder2_(new MockGLES2Decoder());
   TestHelper::SetupContextGroupInitExpectations(gl_.get(),
       DisallowedFeatures(), "");
-  group_->Initialize(DisallowedFeatures(), "");
-  group_->Initialize(DisallowedFeatures(), "");
+  group_->Initialize(decoder_.get(), DisallowedFeatures(), "");
+  group_->Initialize(decoder2_.get(), DisallowedFeatures(), "");
 
   EXPECT_TRUE(group_->buffer_manager() != NULL);
   EXPECT_TRUE(group_->framebuffer_manager() != NULL);
@@ -112,7 +116,7 @@ TEST_F(ContextGroupTest, MultipleContexts) {
   EXPECT_TRUE(group_->program_manager() != NULL);
   EXPECT_TRUE(group_->shader_manager() != NULL);
 
-  group_->Destroy(false);
+  group_->Destroy(decoder_.get(), false);
 
   EXPECT_TRUE(group_->buffer_manager() != NULL);
   EXPECT_TRUE(group_->framebuffer_manager() != NULL);
@@ -121,7 +125,7 @@ TEST_F(ContextGroupTest, MultipleContexts) {
   EXPECT_TRUE(group_->program_manager() != NULL);
   EXPECT_TRUE(group_->shader_manager() != NULL);
 
-  group_->Destroy(false);
+  group_->Destroy(decoder2_.get(), false);
 
   EXPECT_TRUE(group_->buffer_manager() == NULL);
   EXPECT_TRUE(group_->framebuffer_manager() == NULL);
diff --git a/gpu/command_buffer/service/feature_info.cc b/gpu/command_buffer/service/feature_info.cc
index 2a738b8..a7ca864 100644
--- a/gpu/command_buffer/service/feature_info.cc
+++ b/gpu/command_buffer/service/feature_info.cc
@@ -244,6 +244,7 @@ void FeatureInfo::AddFeatures(const char* desired_features) {
   AddExtensionString("GL_CHROMIUM_copy_texture");
   AddExtensionString("GL_CHROMIUM_discard_backbuffer");
   AddExtensionString("GL_CHROMIUM_get_error_query");
+  AddExtensionString("GL_CHROMIUM_lose_context");
   AddExtensionString("GL_CHROMIUM_pixel_transfer_buffer_object");
   AddExtensionString("GL_CHROMIUM_rate_limit_offscreen_context");
   AddExtensionString("GL_CHROMIUM_resize");
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder.cc b/gpu/command_buffer/service/gles2_cmd_decoder.cc
index a6a3055..2d80b70 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -1469,8 +1469,8 @@ class GLES2DecoderImpl : public GLES2Decoder {
   // the tracing system.
   size_t GetBackbufferMemoryTotal();
 
-  // Returns true if the context was just lost due to e.g. GL_ARB_robustness.
   virtual bool WasContextLost() OVERRIDE;
+  virtual void LoseContext(uint32 reset_status) OVERRIDE;
 
 #if defined(OS_MACOSX)
   void ReleaseIOSurfaceForTexture(GLuint texture_id);
@@ -2162,7 +2162,7 @@ bool GLES2DecoderImpl::Initialize(
   context_ = context;
   surface_ = surface;
 
-  if (!group_->Initialize(disallowed_features, allowed_extensions)) {
+  if (!group_->Initialize(this, disallowed_features, allowed_extensions)) {
     LOG(ERROR) << "GpuScheduler::InitializeCommon failed because group "
                << "failed to initialize.";
     group_ = NULL;  // Must not destroy ContextGroup if it is not initialized.
@@ -3059,7 +3059,7 @@ void GLES2DecoderImpl::Destroy(bool have_context) {
   }
 
   if (group_) {
-    group_->Destroy(have_context);
+    group_->Destroy(this, have_context);
     group_ = NULL;
   }
 
@@ -8869,6 +8869,9 @@ error::ContextLostReason GLES2DecoderImpl::GetContextLostReason() {
 }
 
 bool GLES2DecoderImpl::WasContextLost() {
+  if (reset_status_ != GL_NO_ERROR) {
+    return true;
+  }
   if (context_->WasAllocatedUsingRobustnessExtension()) {
     GLenum status = GL_NO_ERROR;
     if (has_robustness_extension_)
@@ -8877,14 +8880,53 @@ bool GLES2DecoderImpl::WasContextLost() {
       // The graphics card was reset. Signal a lost context to the application.
       reset_status_ = status;
       LOG(ERROR) << (surface_->IsOffscreen() ? "Offscreen" : "Onscreen")
-                 << " context lost via ARB/EXT_robustness. Reset status = 0x"
-                 << std::hex << status << std::dec;
+                 << " context lost via ARB/EXT_robustness. Reset status = "
+                 << GLES2Util::GetStringEnum(status);
       return true;
     }
   }
   return false;
 }
 
+void GLES2DecoderImpl::LoseContext(uint32 reset_status) {
+  // Only loses the context once.
+  if (reset_status_ != GL_NO_ERROR) {
+    return;
+  }
+
+  // Marks this context as lost.
+  reset_status_ = reset_status;
+  current_decoder_error_ = error::kLostContext;
+
+  // Loses the parent's context.
+  if (parent_) {
+    parent_->LoseContext(reset_status);
+  }
+
+  // Loses any child contexts.
+  for (ChildList::iterator it = children_.begin();
+       it != children_.end();
+       ++it) {
+    (*it)->LoseContext(reset_status);
+  }
+}
+
+error::Error GLES2DecoderImpl::HandleLoseContextCHROMIUM(
+    uint32 immediate_data_size, const gles2::LoseContextCHROMIUM& c) {
+  GLenum current = static_cast<GLenum>(c.current);
+  GLenum other = static_cast<GLenum>(c.other);
+  if (!validators_->reset_status.IsValid(current)) {
+    SetGLErrorInvalidEnum("glLoseContextCHROMIUM", current, "current");
+  }
+  if (!validators_->reset_status.IsValid(other)) {
+    SetGLErrorInvalidEnum("glLoseContextCHROMIUM", other, "other");
+  }
+  group_->LoseContexts(other);
+  reset_status_ = current;
+  current_decoder_error_ = error::kLostContext;
+  return error::kLostContext;
+}
+
 bool GLES2DecoderImpl::GenQueriesEXTHelper(
     GLsizei n, const GLuint* client_ids) {
   for (GLsizei ii = 0; ii < n; ++ii) {
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder.h b/gpu/command_buffer/service/gles2_cmd_decoder.h
index 4311198..1b36dcb0 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.h
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.h
@@ -195,8 +195,12 @@ class GPU_EXPORT GLES2Decoder : public base::SupportsWeakPtr<GLES2Decoder>,
   virtual base::TimeDelta GetTotalProcessingCommandsTime() = 0;
   virtual void AddProcessingCommandsTime(base::TimeDelta) = 0;
 
+  // Returns true if the context was just lost due to e.g. GL_ARB_robustness.
   virtual bool WasContextLost() = 0;
 
+  // Lose this context.
+  virtual void LoseContext(uint32 reset_status) = 0;
+
   static bool IsAngle();
 
   // Used for testing only
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder_mock.h b/gpu/command_buffer/service/gles2_cmd_decoder_mock.h
index e92ca94..363dfcb 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder_mock.h
+++ b/gpu/command_buffer/service/gles2_cmd_decoder_mock.h
@@ -85,6 +85,7 @@ class MockGLES2Decoder : public GLES2Decoder {
   MOCK_METHOD0(GetTotalProcessingCommandsTime, base::TimeDelta());
   MOCK_METHOD1(AddProcessingCommandsTime, void(base::TimeDelta));
   MOCK_METHOD0(WasContextLost, bool());
+  MOCK_METHOD1(LoseContext, void(uint32 reset_status));
 
   DISALLOW_COPY_AND_ASSIGN(MockGLES2Decoder);
 };
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder_unittest_3_autogen.h b/gpu/command_buffer/service/gles2_cmd_decoder_unittest_3_autogen.h
index 983269b..f644348 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder_unittest_3_autogen.h
+++ b/gpu/command_buffer/service/gles2_cmd_decoder_unittest_3_autogen.h
@@ -66,5 +66,7 @@
 
 // TODO(gman): DiscardFramebufferEXT
 // TODO(gman): DiscardFramebufferEXTImmediate
+// TODO(gman): LoseContextCHROMIUM
+
 #endif  // GPU_COMMAND_BUFFER_SERVICE_GLES2_CMD_DECODER_UNITTEST_3_AUTOGEN_H_
 
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder_unittest_base.cc b/gpu/command_buffer/service/gles2_cmd_decoder_unittest_base.cc
index 4629284..b2c63fb 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder_unittest_base.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder_unittest_base.cc
@@ -13,6 +13,7 @@
 #include "gpu/command_buffer/common/gles2_cmd_utils.h"
 #include "gpu/command_buffer/service/cmd_buffer_engine.h"
 #include "gpu/command_buffer/service/context_group.h"
+#include "gpu/command_buffer/service/gles2_cmd_decoder_mock.h"
 #include "gpu/command_buffer/service/program_manager.h"
 #include "gpu/command_buffer/service/vertex_attrib_manager.h"
 #include "gpu/command_buffer/service/test_helper.h"
@@ -97,7 +98,12 @@ void GLES2DecoderTestBase::InitDecoder(
   TestHelper::SetupContextGroupInitExpectations(gl_.get(),
       DisallowedFeatures(), extensions);
 
-  EXPECT_TRUE(group_->Initialize(DisallowedFeatures(), NULL));
+  // We initialize the ContextGroup with a MockGLES2Decoder so that
+  // we can use the ContextGroup to figure out how the real GLES2Decoder
+  // will initialize itself.
+  mock_decoder_.reset(new MockGLES2Decoder());
+  EXPECT_TRUE(
+      group_->Initialize(mock_decoder_.get(), DisallowedFeatures(), NULL));
 
   AddExpectationsForVertexAttribManager();
 
@@ -295,7 +301,7 @@ void GLES2DecoderTestBase::TearDown() {
 
   decoder_->Destroy(true);
   decoder_.reset();
-  group_->Destroy(false);
+  group_->Destroy(mock_decoder_.get(), false);
   engine_.reset();
   ::gfx::GLInterface::SetGLInterface(NULL);
   gl_.reset();
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder_unittest_base.h b/gpu/command_buffer/service/gles2_cmd_decoder_unittest_base.h
index 420351e..7a1f975 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder_unittest_base.h
+++ b/gpu/command_buffer/service/gles2_cmd_decoder_unittest_base.h
@@ -466,6 +466,7 @@ class GLES2DecoderTestBase : public testing::Test {
   scoped_ptr< ::testing::StrictMock< ::gfx::MockGLInterface> > gl_;
   scoped_refptr<gfx::GLSurfaceStub> surface_;
   scoped_refptr<gfx::GLContextStub> context_;
+  scoped_ptr<GLES2Decoder> mock_decoder_;
   scoped_ptr<GLES2Decoder> decoder_;
 
   GLuint client_buffer_id_;
diff --git a/gpu/command_buffer/service/gles2_cmd_validation_autogen.h b/gpu/command_buffer/service/gles2_cmd_validation_autogen.h
index c19ba38..7e41788 100644
--- a/gpu/command_buffer/service/gles2_cmd_validation_autogen.h
+++ b/gpu/command_buffer/service/gles2_cmd_validation_autogen.h
@@ -44,6 +44,7 @@ ValueValidator<GLenum> read_pixel_type;
 ValueValidator<GLenum> render_buffer_format;
 ValueValidator<GLenum> render_buffer_parameter;
 ValueValidator<GLenum> render_buffer_target;
+ValueValidator<GLenum> reset_status;
 ValueValidator<GLenum> shader_binary_format;
 ValueValidator<GLenum> shader_parameter;
 ValueValidator<GLenum> shader_precision;
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 d951e79..1f8535b 100644
--- a/gpu/command_buffer/service/gles2_cmd_validation_implementation_autogen.h
+++ b/gpu/command_buffer/service/gles2_cmd_validation_implementation_autogen.h
@@ -336,6 +336,12 @@ static GLenum valid_render_buffer_target_table[] = {
   GL_RENDERBUFFER,
 };
 
+static GLenum valid_reset_status_table[] = {
+  GL_GUILTY_CONTEXT_RESET_ARB,
+  GL_INNOCENT_CONTEXT_RESET_ARB,
+  GL_UNKNOWN_CONTEXT_RESET_ARB,
+};
+
 static GLenum valid_shader_parameter_table[] = {
   GL_SHADER_TYPE,
   GL_DELETE_STATUS,
@@ -597,6 +603,8 @@ Validators::Validators()
       render_buffer_target(
           valid_render_buffer_target_table, arraysize(
               valid_render_buffer_target_table)),
+      reset_status(
+          valid_reset_status_table, arraysize(valid_reset_status_table)),
       shader_binary_format(),
       shader_parameter(
           valid_shader_parameter_table, arraysize(
diff --git a/gpu/command_buffer/tests/gl_lose_context_chromium_unittests.cc b/gpu/command_buffer/tests/gl_lose_context_chromium_unittests.cc
new file mode 100644
index 0000000..385cc88
--- /dev/null
+++ b/gpu/command_buffer/tests/gl_lose_context_chromium_unittests.cc
@@ -0,0 +1,63 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <GLES2/gl2.h>
+#include <GLES2/gl2ext.h>
+
+#include "base/logging.h"
+#include "gpu/command_buffer/tests/gl_manager.h"
+#include "gpu/command_buffer/tests/gl_test_utils.h"
+#include "testing/gmock/include/gmock/gmock.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace gpu {
+
+class GLLoseContextTest : public testing::Test {
+ protected:
+  virtual void SetUp() {
+    GLManager::Options options;
+    gl2_.Initialize(options);
+    options.context_lost_allowed = true;
+    gl1a_.Initialize(options);
+    options.share_group_manager = &gl1a_;
+    gl1b_.Initialize(options);
+  }
+
+  virtual void TearDown() {
+    gl1a_.Destroy();
+    gl1b_.Destroy();
+    gl2_.Destroy();
+  }
+
+  GLManager gl1a_;
+  GLManager gl1b_;
+  GLManager gl2_;
+};
+
+// Test that glLoseContextCHROMIUM loses context in the same
+// share group but not other.
+TEST_F(GLLoseContextTest, ShareGroup) {
+  gl1a_.MakeCurrent();
+  glLoseContextCHROMIUM(
+      GL_GUILTY_CONTEXT_RESET_EXT, GL_INNOCENT_CONTEXT_RESET_EXT);
+
+  uint8 expected_no_draw[] = {
+    GLTestHelper::kCheckClearValue,
+    GLTestHelper::kCheckClearValue,
+    GLTestHelper::kCheckClearValue,
+    GLTestHelper::kCheckClearValue,
+  };
+  // Expect the read will fail.
+  EXPECT_TRUE(GLTestHelper::CheckPixels(0, 0, 1, 1, 0, expected_no_draw));
+  gl1b_.MakeCurrent();
+  // Expect the read will fail.
+  EXPECT_TRUE(GLTestHelper::CheckPixels(0, 0, 1, 1, 0, expected_no_draw));
+  gl2_.MakeCurrent();
+  uint8 expected_draw[] = { 0, 0, 0, 0, };
+  // Expect the read will succeed.
+  EXPECT_TRUE(GLTestHelper::CheckPixels(0, 0, 1, 1, 0, expected_draw));
+}
+
+}  // namespace gpu
+
diff --git a/gpu/command_buffer/tests/gl_manager.cc b/gpu/command_buffer/tests/gl_manager.cc
index 6ec3097..57abc34 100644
--- a/gpu/command_buffer/tests/gl_manager.cc
+++ b/gpu/command_buffer/tests/gl_manager.cc
@@ -29,10 +29,12 @@ GLManager::Options::Options()
       share_group_manager(NULL),
       share_mailbox_manager(NULL),
       virtual_manager(NULL),
-      bind_generates_resource(false) {
+      bind_generates_resource(false),
+      context_lost_allowed(false) {
 }
 
-GLManager::GLManager() {
+GLManager::GLManager()
+    : context_lost_allowed_(false) {
 }
 
 GLManager::~GLManager() {
@@ -45,6 +47,8 @@ void GLManager::Initialize(const GLManager::Options& options) {
   const size_t kMaxTransferBufferSize = 16 * 1024 * 1024;
   const bool kShareResources = true;
 
+  context_lost_allowed_ = options.context_lost_allowed;
+
   gles2::MailboxManager* mailbox_manager = NULL;
   if (options.share_mailbox_manager) {
     mailbox_manager = options.share_mailbox_manager->mailbox_manager();
@@ -198,7 +202,9 @@ void GLManager::PumpCommands() {
   decoder_->MakeCurrent();
   gpu_scheduler_->PutChanged();
   ::gpu::CommandBuffer::State state = command_buffer_->GetState();
-  ASSERT_EQ(::gpu::error::kNoError, state.error);
+  if (!context_lost_allowed_) {
+    ASSERT_EQ(::gpu::error::kNoError, state.error);
+  }
 }
 
 bool GLManager::GetBufferChanged(int32 transfer_buffer_id) {
diff --git a/gpu/command_buffer/tests/gl_manager.h b/gpu/command_buffer/tests/gl_manager.h
index 5f42a36..2b24331 100644
--- a/gpu/command_buffer/tests/gl_manager.h
+++ b/gpu/command_buffer/tests/gl_manager.h
@@ -48,6 +48,8 @@ class GLManager {
     GLManager* virtual_manager;
     // Whether or not glBindXXX generates a resource.
     bool bind_generates_resource;
+    // Whether or not it's ok to lose the context.
+    bool context_lost_allowed;
   };
   GLManager();
   ~GLManager();
@@ -87,6 +89,7 @@ class GLManager {
   scoped_ptr<gles2::GLES2CmdHelper> gles2_helper_;
   scoped_ptr<TransferBuffer> transfer_buffer_;
   scoped_ptr<gles2::GLES2Implementation> gles2_implementation_;
+  bool context_lost_allowed_;
 };
 
 }  // namespace gpu
diff --git a/gpu/command_buffer/tests/gl_test_utils.cc b/gpu/command_buffer/tests/gl_test_utils.cc
index f4ea96b..1a3e7c2 100644
--- a/gpu/command_buffer/tests/gl_test_utils.cc
+++ b/gpu/command_buffer/tests/gl_test_utils.cc
@@ -10,6 +10,11 @@
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
+// GCC requires these declarations, but MSVC requires they not be present.
+#ifndef COMPILER_MSVC
+const uint8 GLTestHelper::kCheckClearValue;
+#endif
+
 bool GLTestHelper::HasExtension(const char* extension) {
   std::string extensions(
       reinterpret_cast<const char*>(glGetString(GL_EXTENSIONS)));
@@ -108,7 +113,7 @@ bool GLTestHelper::CheckPixels(
     const uint8* color) {
   GLsizei size = width * height * 4;
   scoped_array<uint8> pixels(new uint8[size]);
-  memset(pixels.get(), 123, size);
+  memset(pixels.get(), kCheckClearValue, size);
   glReadPixels(x, y, width, height, GL_RGBA, GL_UNSIGNED_BYTE, pixels.get());
   bool same = true;
   for (GLint yy = 0; yy < height; ++yy) {
diff --git a/gpu/command_buffer/tests/gl_test_utils.h b/gpu/command_buffer/tests/gl_test_utils.h
index bd2d380..31de7cd 100644
--- a/gpu/command_buffer/tests/gl_test_utils.h
+++ b/gpu/command_buffer/tests/gl_test_utils.h
@@ -12,6 +12,8 @@
 
 class GLTestHelper {
  public:
+  static const uint8 kCheckClearValue = 123u;
+
   static bool HasExtension(const char* extension);
   static bool CheckGLError(const char* msg, int line);
 
diff --git a/gpu/gpu.gyp b/gpu/gpu.gyp
index e7bd419..e3ccb37 100644
--- a/gpu/gpu.gyp
+++ b/gpu/gpu.gyp
@@ -238,6 +238,7 @@
         'command_buffer/tests/gl_copy_texture_CHROMIUM_unittest.cc',
         'command_buffer/tests/gl_depth_texture_unittest.cc',
         'command_buffer/tests/gl_query_unittests.cc',
+        'command_buffer/tests/gl_lose_context_chromium_unittests.cc',
         'command_buffer/tests/gl_manager.cc',
         'command_buffer/tests/gl_manager.h',
         'command_buffer/tests/gl_pointcoord_unittest.cc',
diff --git a/third_party/khronos/GLES2/gl2ext.h b/third_party/khronos/GLES2/gl2ext.h
index 35a28cb9..6cbca97 100644
--- a/third_party/khronos/GLES2/gl2ext.h
+++ b/third_party/khronos/GLES2/gl2ext.h
@@ -2173,6 +2173,15 @@ typedef void (GL_APIENTRYP PFNGLRELEASETEXIMAGE2DCHROMIUM) (GLenum target, GLint
 #define GL_ASYNC_PIXEL_TRANSFERS_COMPLETED_CHROMIUM 0x84F5
 #endif
 
+/* GL_CHROMIUM_lose_context */
+#ifndef GL_CHROMIUM_lose_context
+#define GL_CHROMIUM_lose_context 1
+#ifdef GL_GLEXT_PROTOTYPES
+GL_APICALL void GL_APIENTRY glLoseContextCHROMIUM (GLenum current, GLenum other);
+#endif
+typedef void (GL_APIENTRYP PFNGLLOSECONTEXTCHROMIUM) (GLenum current, GLenum other);
+#endif
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/third_party/khronos/README.chromium b/third_party/khronos/README.chromium
index 7760f41..36caefa 100644
--- a/third_party/khronos/README.chromium
+++ b/third_party/khronos/README.chromium
@@ -21,20 +21,21 @@ GLES2/gl2.h
  - Added include of gl2chromium.h
 GLES2/gl2ext.h
  - Added Chromium and Angle extensions.
- - Added ANGLE_instanced_arrays
+ - Added GL_ANGLE_instanced_arrays
  - Added GL_ARB_robustness (subsetted)
  - Added GL_ARB_texture_rectangle (subsetted)
- - Added GL_EXT_framebuffer_multisample
- - Added GL_CHROMIUM_command_buffer_query
+ - Added GL_CHROMIUM_async_pixel_transfers
+ - Added GL_CHROMIUM_bind_uniform_location
  - Added GL_CHROMIUM_command_buffer_latency_query
+ - Added GL_CHROMIUM_command_buffer_query
  - Added GL_CHROMIUM_copy_texture
- - Added GL_CHROMIUM_bind_uniform_location
  - Added GL_CHROMIUM_get_error_query
+ - Added GL_CHROMIUM_gpu_memory_manager
  - Added GL_CHROMIUM_iosurface
- - Added GL_CHROMIUM_texture_from_image
+ - Added GL_CHROMIUM_lose_context
  - Added GL_CHROMIUM_pixel_transfer_buffer_object
- - Added GL_CHROMIUM_async_pixel_transfers
- - Added GL_CHROMIUM_gpu_memory_manager
+ - Added GL_CHROMIUM_texture_from_image
+ - Added GL_EXT_framebuffer_multisample
  - Added GL_NVX_gpu_memory_info
  - Added include of gl2chromium.h
 EGL/eglplatform.h