Dump from pasko@ and lizeb@ investigation:

Strings are large. Here's how much:

$ zcat out/Release/lib.unstripped/libchrome.so.map.gz | less
[...]
.rodata         0x02572700   0x5e3ca0
 ** merge strings
                0x02572700   0x2ad68b
[...]

Dumping the strings:
$ dd if=out/Release/lib.unstripped/libchrome.so of=strings.txt bs=1 skip=39266048 count=2807435

(0x02572700 == 39266048, 0x2ad68b == 2807435)

$ $EDITOR strings.txt

From a visual inspection:
- Lots of things from __FILE__:__LINE__
- Error messages
- Shader source code
- JNI signature for registration: >67K
- Tracing event names, histograms: >140K

Most of it looks "infrequently" used. At the same time, .rodata is almost always loaded in memory, and marked executable (same segment as .text), hence hard to evict for the kernel.