gpu: Fix some context lost marking glitches+leaks and add UMA stats

gpu/command_buffer/common/constants.h

 // 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.
 
 #ifndef GPU_COMMAND_BUFFER_COMMON_CONSTANTS_H_
 #define GPU_COMMAND_BUFFER_COMMON_CONSTANTS_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
 namespace gpu {
 
 typedef int32_t CommandBufferOffset;
 const CommandBufferOffset kInvalidCommandBufferOffset = -1;
 
 // This enum must stay in sync with NPDeviceContext3DError.
 namespace error {
   enum Error {
     kNoError,
     kInvalidSize,
     kOutOfBounds,
     kUnknownCommand,
     kInvalidArguments,
     kLostContext,
     kGenericError,
-    kDeferCommandUntilLater
+    kDeferCommandUntilLater,
+    kErrorLast = kDeferCommandUntilLater,
   };
 
   // Return true if the given error code is an actual error.
   inline bool IsError(Error error) {
     return error != kNoError && error != kDeferCommandUntilLater;
   }
 
   // Provides finer grained information about why the context was lost.
   enum ContextLostReason {
     // This context definitely provoked the loss of context.
     kGuilty,
 
     // This context definitely did not provoke the loss of context.
     kInnocent,
 
     // It is unknown whether this context provoked the loss of context.
     kUnknown,
-    kContextLostReasonLast = kUnknown
+
+    // GL_OUT_OF_MEMORY caused this context to be lost.
+    kOutOfMemory,
+
+    // A failure to make the context current caused it to be lost.
+    kMakeCurrentFailed,
+
+    // The GPU channel was lost. This error is set client-side.
+    kGpuChannelLost,
+
+    kContextLostReasonLast = kGpuChannelLost
   };
 }
 
 // Invalid shared memory Id, returned by RegisterSharedMemory in case of
 // failure.
 const int32_t kInvalidSharedMemoryId = -1;
 
 // Common Command Buffer shared memory transfer buffer ID.
 const int32_t kCommandBufferSharedMemoryId = 4;
 
 // The size to set for the program cache.
 const size_t kDefaultMaxProgramCacheMemoryBytes = 6 * 1024 * 1024;
 
 }  // namespace gpu
 
 #endif  // GPU_COMMAND_BUFFER_COMMON_CONSTANTS_H_