Move a bunch of code in content\common (as well as a few left in renderer) to the content namespace.

content/common/gpu/gpu_memory_tracking.h

Index: content/common/gpu/gpu_memory_tracking.h
===================================================================
--- content/common/gpu/gpu_memory_tracking.h	(revision 163290)
+++ content/common/gpu/gpu_memory_tracking.h	(working copy)
@@ -10,6 +10,8 @@
 #include "base/basictypes.h"
 #include "content/common/gpu/gpu_memory_manager.h"
 
+namespace content {
+
 // All decoders in a context group point to a single GpuMemoryTrackingGroup,
 // which tracks GPU resource consumption for the entire context group.
 class GpuMemoryTrackingGroup {
@@ -48,6 +50,8 @@
   GpuMemoryManager* memory_manager_;
 };
 
+}  // namespace content
+
 #endif
 
 #endif // CONTENT_COMMON_GPU_GPU_MEMORY_TRACKING_H_